It’s not hard to recover the combination to a combination lock. With three numbers ranging from 0 to 39 there are 64,000 possible combinations and attempting to brute force a solution at 10 seconds per try could take 22 days of non-stop testing. With this technique it will take only 15 minutes without any experience. After you’re successful, it takes less than 10 minutes to crack the combination. I’ve even included a program that will help narrow down the possibilities and make the process quick and painless.

This procedure was designed for Master Lock brand combination locks new and old. The illustration shown to the right illustrates the “slop” in the mechanics of the lock. A combination of 22-10-17 is the same as 22-11-17 or 22-9-17. This makes Master Lock combination recovery a lot easier.

### Step 1. Make a list of possible last numbers of the combination.

- Turn the dial clockwise past zero three times and leave it set to zero.
- Apply even tension to the metal shackle (U-shaped part) by pulling down if it’s attached to something or pulling up if you’re holding it in your hand. This causes the dial to stick and not turn easily. So, apply just enough tension and turn the dial clockwise until it stops. Note whether it stops right on a number or between two numbers. While still applying tension turn the dial counter-clockwise (left) to find the range.
- If the range is between two numbers say 17 and 18, record the number as 17.5. If, on the other hand, the range is in the middle of two numbers, say 20.5 and 21.5 record the number as 21. This is the middle of the range. You can rest between numbers; it won’t affect the solution.
- You can release some tension from the shackle to get past the sticking point to find the next sticking point. Repeat this process until you get to zero.

**HINT:**The dial should stick every 3-4 numbers.

### Step 2. Find the last number of the combination.

In one complete turn of the dial you should have 12 numbers recorded. 7 of the numbers should be fractions ending in .5 – these can be eliminated. Of the remaining 5 the last number in the combination is the whole number with the unique ending. For example, with my test lock I listed the following numbers:

38, 34.5, 31, 27.5, 24.5, 21, 17.5, 14.5, 11, 7.5, 4.5, 1. removing the fractions and the similar numbers ending in 1 leaves 38, the only number ending in something other than 1.

### Step 3. Calculate the possible combinations.

Select the number you found in Step 2 into the Combination Calculator. It will calculate all the possible combinations, 64 in total, much fewer than 64,000, and it usually takes, on average, only 32 tries to find the correct combination.

**Hint:** And in case you forgot, it’s always twice past zero turning clockwise (right) to the first number, once past zero to the second number counter-clockwise (left), and finally clockwise (right again) to the last number.

Good Luck.

Did the link to the calculator stop workng?

This worked great for me earlier this week.

I came across another lock, when I tried the link to the calculator today, a few days later, I’m getting an error saying it can’t be found.

🙁

Just did a server upgrade. All the files are back online. Thank you very much for taking the time to let me know.

Thank you! I’ve been trying other methods on and off for a few days trying to get my Master Lock open. (It has a 905xxx serial number on the back.) This finally worked. Interestingly, some of the other methods HAD correctly identified the last number, but first number was never correctly identified.

It worked. Add me to the list. I had to double-check one of the ‘eliminated’ numbers, with another turn of the dail. Common numbers had an ending of 4, leaving the last number in the combination.

Nearly went through the whole combination chart. Yet, Pop! there it was. Thanks for the procedure.

I have an older master lock and the dial only goes up to 19. It says “hardened” on the shackle and “3117” on the back but nothing else and no key hole. I tried the method but its putting my last number possibilities in the 20s or 30s, which I don’t have. Can you help?

Ok, tried 18-8-26 from the ComboCalculator and it opens the lock..

My guess is that is most likely the Factory Combo..

My original last # was picked as 9 – guided in part by the Samy Kamkar method which didn’t work..

The 12 points were: (2.5, 12.5, 22.5, 32.5,

6, 16, 26.25, 36,

9.25, 19.25, 29.25, 39.25)

Tried the formula method which has opened several MasterLocks in the past, but a lock I found does not match the formula. Lock is Ser#9099xx series and had to shim it open. The combo determined from lining up the 3 discs is 19-07-27 (the middle number does not fit the standard formula of +/- 2 from the 1st & 3rd numbers.

I was also able to open it using 18.5-6.5-26.5 but other variations (+/- 0.5) did not work.

Thank you for sharing the procedure of master lock combination recovery. These guidelines will help anyone to recover the combination to a combination lock.

I knew the last digit of my combination – The calculator worked brilliantly – I had my lock open in about 3 minutes! Thank you SO much (I’ve had this lock for 40+ years and I was sad to think I might have to destroy it to get my locker open…)

Cheers!

38

35

31.5

28.5

25

21.5

18

14.5

11.5

8

4.5

1.5

I’m not sure which numbers I’m supposed to take out out of the whole numbers I found. I’ve done this a few times and still can’t unlock it.

Did you try 35?

my high school coach showed me how to get combinations using formula applied to serial numbers but that was 50 years ago. does this still work today and what is formula

This method uses an algorithm which uses formulas.

You can see it here:

https://blog.dreamshire.com/source-code-for-master-lock-combination-calculator/

All my daughter could remember is that the combo had a low number in the middle. After looking at different tutorials, I kept coming up with 36 as the last number. The possibles table was a great tool. Was able to open after about 10 tries.

Thanks!!

Well, it’s faster than trying all combinations, but just trying to figure out the “slight pressure” on the shackle has been ridiculous. Probably faster to just send in a lost combination form and wait the 4 to 6 weeks.

Yippee! I wanted to give this lock to my granddaughter for her work locker but couldn’t remember combination. It took a bit of time but once I realized how much tension I needed to feel the stops I hit my numbers. I had a few numbers that could have been either fractions or whole numbers but since I knew there were 7 fractions I crossed those off and was able to figure out my last number. After that it took about 5 minutes. Thx

I have a Master Glo lock which is similar to the Sphero and has a serial number on the back that starts with 800. The last number has to be 33, since that is the largest sticking point by far ranging from 31-34 and I have read that Spheros usually have one wide point that is the correct number. However, all the combinations I have tried using the calculator have failed. Any suggestions? Is there a different algorithm for the other two number sets? Thanks!

My Numbers are 2.5, 6, 9.5, 12.5, 16, 19.5, 22.5, 26, 29.5, 32.5, 36, 39.5….Please guide what will be the last number..Thanks

One of your fractional numbers could be in error. Try again as one will be a whole number and that’s the one you want. If I had to guess I would try 2.

Beautiful… got my lock back!

Worked like a charm only 48 tries

I tried your calculator without any success. Just now, I found a note with the real combination on it, and it is not included in the calculator results. Clearly, Master Lock has updated their algorithms.

I too have a Master Combination lock with the code 35-16-1 not in the solution set 🙁

This is because 35-16-1 is the same combination as 36-16-1, 35-17-1, 34-16-2 and many other combinations up to 2 numbers away from the original. The mechanism is not very precise and allows for this variance to happen although the degree of variance differs from lock to lock.

My master lock has both a dial for combinations and a key hole in the back. This method doesn’t seem to work for this type of master locks.

The key hole was to allow access for school issued locks. This method does work on those locks as well. Just make sure you have the correct last number.

Worked like a champ! Figured out the last number and I knew there was a 30# in there somewhere so that narrowed it down a bit. Took a minute then pop!

Thanks!

Sweet!!! Just used this to open by old college Master Lock from the 80’s that I found up in the attic. I can now use it at the gym. Love it, no need to toss my ole favorite after all these years.

I can not figure this out. My numbers are 38, 33.5, 30.5,27,23.5,20.5,17,13.5,10,7,3.5

I would say that 10 is your last number. Imagine that 38 is actually 37 and that would cancel the numbers ending in 7. You’d also have cancelled the decimal numbers and so 10 would be your best bet.

Could you please explain why the “bands” of unused solutions on the combination page? (e.g. my last number is 5, and the possible solution space I have calculated are:

First Number: 1,5,9,13,17,21,25,29,33,37

Second Number: 3,7,11,15,19,23,27,31,35,39

But in the “combination calculation” page, it omits the first two lines (1-3-5, 1-7-5, 1-11-5… 1-39-5 and 5-3-5, 5-7-5, 5-11-5, … 5-39-5) as well as having diagonal empty boxes in the solution space.

This seems intuitive to me, but I’m not certain why these possible solutions are removed.

Thanks! Just trying to learn.

On the right side I thought I had remembered the first two numbers and using your method I found the last number and the combinations showed 1 the transposed the first two digits I had remembered. Long story short I tried that and it took less than 5 minutes thank you

someone locked my lock at school and I cant try to do this because it will take to long and all my suff is in my locker!!!! help!

It only takes about 15 minutes. Just give it a try.

Thanks for the info! Worked after 35 tries. Just followed the steps very carefully and was shocked! It worked!! Thanks again….

You’re welcome. Glad it worked out.

Need help with this lock. Here are my numbers.

0, 3.5, 7, 10, 13.5, 17, 20, 23.5, 27, 30, 33.5, 37

My son thought the last number was 39 but that isn’t working. Help, please?!?

You may want to try 0 as the last number. This may be an older, well used lock and the mechanics could be a bit worn. Let me know if this solves the problem. Good Luck.

I have similar numbers to you, and depending on how I interpreted if a number was a fraction or a whole, I ended up with either 37 or 0 as the final number. 37 and 0 were my only definite whole numbers, the rest were borderline.

I reccomend revisiting all your whole numbers and pull the shackle hard while you juggle the dial within each sticking point. When doing this on your 3rd number, you should feel no resistance on the dial even when pulling very hard on the shackle. You will find resistance at the dial when you do this at all other stopping points. I read this tip years ago on a different website, and I don’t know if it holds true 100% of the time, but it works for both my locks.

Sorry bother but i don’t know it’s me but confuse on this abit and I don’t know which can b the third number..tried but stuck

0,3,6.5,10,13,16.5,19.5,23,26.5,30,33,36.5

Old blue master lock.

Thanks hope u can help

Your last number is probably 24. You may want to give this a try.

Well, well, thank you!

I found my pretty green “hardened” MASTERlock I bought ages ago in college, but jumbling lost the little slip of paper with the combination code on it.

I followed the code-cracking instructions on it, and about 3/4 the way through the potential solution space, found the code!

I Tested it twice, it definitely is the code.

Thank you so much!

You’re welcome. Glad it could help.

Only came up with 10 numbers and they all seemed to be .5’s. So I check again and picked the 1 that came closest. Put that into the calculator, decided to start with the middle row and 6 combo’s later POP. Excellent method. THANKS!

So I’ve been doing this for years and have never had an issue…until now. I have a Master lock that is not just being stubborn…it’s being downright impossible. Brand new, never been used, but my friend threw the packaging (and thus the combination) away like a good little idiot. Anyway, she gave it to me and I picked out the sticking points, but here’s where it’s weird: nine of the numbers are fractions and the other three numbers all have the same last digit. There’s no wear on the lock, and it is very definite where the sticking points are – no hesitation or unusual movements. The numbers are as follows:

37.5, 34.5, 30.5, 27.5, 24, 20.5, 17.5, 14, 10.5, 7.5, 4, .5

Having cracked dozens upon dozens of these locks in the past twenty years, I admit to being stumped by this one. Little pain in the rear. 😛 Any input would be appreciated. Meanwhile…back to the lock.

Is it the same set of numbers going CCW? Based on the list I’d say the unique 1s digit is the 34.5. Perhaps this lock was a simple one in a million defect.

I’ve come across 2 I couldn’t crack. One of them was damaged and then 1s digit was definitely a decimal. Garbaged it. The other is a master lock sphere.

Don’t know if you have the lock anymore or will see this, but I had the same numbers as you and my code was 4-10-4.

So I used this to open several locks but I have one that’s being a pain.

Here’s the numbers:

39,35.5,32.5, 29,26,22.5,19,15.5,12.5,9,6,2.5

Eliminate the fractions:

39,29,26,19,9,6

Eliminate similar number:

No numbers remain

?????

Try 0?

Wear on the lock could make some of the ranges wider and cause errors. Assuming only one error, either the 26 should be 25.5, or the 6 should be 5.5. So the last number is either 26 or 6.

Notice the pattern in the numbers. If you arrange the numbers in four row, three numbers in each row, you have one column ending in an integer, one column ending in a fraction, and one mixed column. The last number of the combination should be the only integer in the mixed column. Your mixed column has two integers, so one of the integers must be wrong.

Your “Hint: And in case you forgot …” is not quite correct.

“Twice past zero turning clockwise” might not be enough. If your combination is (for example) 36-2-8, and you start from 2, that would give you not much more than one full turn. The Master Lock website recommends three turns clockwise.

“Once past zero to the second number” is not enough either. If you combination is (the same example) 36-2-8, that would give you a small fraction of a turn. The Master Lock website recommends turning past the first number to the second.

So the “Hint” should be “And in case you forgot, it’s always three turns clockwise (right) to the first number, once past the first number to the second number counter-clockwise (left), and finally clockwise (right again) to the last number.”

Two of my combinations number are 32 and 35 as conveyed to me by my uncle who has given me one such lock. he forgot what is third number and where to put that number. Missing number may be on first position, or may be second or may be last. can you suggest me possible combinations.

Further info: The lock is fastened onto a loop of corroded galvanized chain, which reminds me that it’s been used on a boat on salt water. The lock is probably so corroded that the stops don’t work properly, though it might open properly on the right combination. Any hints on how to find the right combination for a corroded lock?

Mike, I have an old Master lock, serial number 900390, and I can’t get started on it. I have nine ranges and three of them are 5 or 6 numbers wide, with no stopping points within them. There must be some missing stop points. Can I calculate them or guess them? Also, many of the stop points are 1/4 of the way between numbers; how do I deal with that?

I need help doing the math on mine. i cant get past the first step which is finding the third number. I do it 3 or 4 times and every time i get 3 as my third number. And 3/4 = .75. HELP Please. Anyone.

Thank you.

Walter, what page are you on?

Once you have 3 as your third number, Step 3 says you click on the Combination Calculator link and select 3 from the drop down list.

There is a completely different page that says you divide your last number by 4 but you only use the remainder, which in this case is 3. We don’t do that here.

It worked like a charm! Thanks so much for posting such a clear and cogent set of directions — and the online calculator for generating the combinations!

I tried and didn’t work for me. I’m wondering why there are no ‘0’ in the combinations? I know my last number is 38 (or i think so). Is there another lock calculator that helps if you know 2 of the numbers? I feel like there’s a ‘0’ in my 3 digits.

Any help would be great. thanks!

33 tries and it worked. Amazing.

Mike, thanks so much for this well-written and extremely helpful post. I had forgotten my combination but was sure I would recognize it if I saw it. Using your Combination Calculator, coupled with the knowledge of the last digit in the combination, I found the complete combination on my first try.

it took 49 tries, but it WORKED!!! Thanks!

I have a lock and I think my last number is 36 can you help?

Thank you. I have a Masterlock that has been on my college bike since 1982.

It took try number 59 out of 64 possibles but it worked.

Thanks again.

That’s awesome! Wow, 32 years. And of course, just to make you pay for it, it would have to be towards the end of the list.

Thanks for the comment!

i’ve tried several times and cannot get it to open. 0.5,4,7.5,11,14,17.5,20.5,24,27.5,30.5,34,37.5

please help asap

Your last number should be 11. Type that into the calculator and try those combinations.

Don’t know if you have the lock anymore or will see this, but I had the same numbers as you and my code was 4-10-4.

Many thanks for the excellent material you are producing.

I do not know what the current Master lock numbers are, but I get from your posts that the standard methods apply to them.

At the moment, I’m trying to work a combination lock that has only one marking: Made in China. The standard method doesn’t work. I’ve shimmed it open and will look inside with an otoscope to get the slots.

I was hoping it was that simple, but I guess we have our work cut out for us. Can you still get the 800 locks? I’m certain it’s just a simple shift in the algorithm and, based on your note, I can try to increase the increment and generate a new table just for these locks.

I, too, need to get my hands on one of these.

Thanks for your info – I didn’t know there was a difference.

Thanks for the tip, Mike.

Those don’t do it, though.

Looking through an old diary entry, I say,”Finally figured out the 800-series locks. The first number can’t be the same as the last, must be 2 off.” That suggests that the standard method, which produces 29-15-29 must be two up on the first number.

Again, I don’t know because I don’t have another 800 lock to test the theory.

Several years ago I cracked an 800 series Master lock using a method I do not recall. It is not the method I have seen repeatedly on the web and discussed here. The combination is 31 – 15 – 29. Note that the first and last numbers are only two apart. There are no table I can now find that support this combination, yet I cracked it using a method I found on the web. Can anyone find such a table or method for these 800 series lock?

Also, I have tried first and last numbers one up and one down from the actual combination without success.

Have a try at 29 – 15 – 29 or 33 – 15 – 29 and let me know if that works. They are in the same horizontal direction and should be equivalent.

I have a hardened master lock and I also only had 4 whole numbers but I didn’t think any of them were particularly loose. Am I able to check two different 3rd numbers at once? That is, if I go 15-25-39 can I keep going and give an extra pull on 19 (as the 3rd number)? Does pulling the lock early invalidate the sequence?

Hi Martin,

Yes, you can try more than one last number and not worry that pulling the shackle will reset the process. Let me know if this works for you. I have opened hundreds of locks with this method (end of school year, students leave them on lockers)

0 was my last number, So I tried all the variations and no luck. I thought I did something wrong, Tried again with 12 as my last number. no luck. Went back to 0 again, lock opened in 26 tries. Must have messed up my first attempt. Thank you.

Found an old Master Combo lock in a drawer and thought I would go online and try to crack it.

Took me about 50 or so tries with the combination output sheet, but I finally got it!

Mucho Thanks!

I will be overjoyed if this works.

Un-f*ing-believable! once I saw the list, I was able to pick out the right combo from memory. Open in a single try! Now I don’t need a new lock. thank you!!

I have tried this method several times , I always get 26 as the last number . I have tried every combo on the chart. But none seem to be the right one. I have checked and re checked but it does not seem to work for me.

Numbers are : 2.5, 5.5 , 9, 12.5, 15.5, 19, 22.5, 26, 29, 32,5 , 35.5, 39

Thank you

We bought a 2-pack with identical combination. We then proceeded to lose the combination. Hence my presence here.

I’m unable to retrieve it as both lock have different sticky points:

39, 35.5, 32.5, 29, 25.5, 22, 18.5/19, 15.5, 12.5, 9, 5.5, 2.5

On this one, I tried 18 and 22 as the last number. Failed.

36.5, 38, 30, 26.5, 23, 19.5, 16.5, 13.5?, 10, 6.5, 3.5, 0

On this one, I tried and 23 and 38 as the last number. Failed again.

The serial number are still sticked to the locks: 1500-05902.

Worked like a charm!

Thanks!!!!

Help. I get five numbers: 9,16,19,36. What is my third number? Or what am I doing wrong?

I have ran the possible combinations 4x, and double checked them the calculator. I still cannot get it open. Help!

I started on another site and could not figure out what the last number was. I kept getting 3 numbers ending in 9 and 2 numbers ending in 6 (39, 35.5, 32.5, 29, 25.5, 22.5, 19, 16, 12.5, 9.5, 6, 2.5). I read thru the posts and found 2 answers that helped:

1. Find the number with a little more range of motion than the rest. Normal range of motion was always really close to 1 except for number 6, which was between 5.5 and 7.

2. I tried counter clockwise just to verify, same result, 5.5 to 7.

I used the calculator specified on this site, and verified it against another at http://www.gliderspen.net/cgi-bin/masterlock.cgi, my combination was on both.

I had a similar problem. I kept trying but couldn’t get it until someone suggested turning the dial counter-clockwise. It worked like a charm.

Good Luck, hope this helps you.

After reading other comments it seems a few other people have the same problem I have. My numbers are 2.5,6,9,12.5,16,19,22.5,26,29, 32.5,36 and 39. I’ve used this method on other locks and it worked but I can’t figure this one out. Anyone else figure this out?

6 was my third number. After checking the numbers again I realized that the range of motion was slightly greater at 6 than at 16, 26, and 36. If anyone else is having the same problem check your numbers again if one of the four #’s ending in 6 or the four #’s ending in 9 move slightly more to the left or right than the other three #’s this could be your third number. You really have to look close because there was only a very little difference in my case. Worst case scenario try all 8 whole numbers as your third number. This could take some time though. I also read somewhere that you can eliminate two out the ten second numbers (2 numbers above and 2 numbers below whatever your 3rd number is). This narrows down the posible combinations from 100 to 80. I hope this helps.

Thanks for the feedback Jeff, this will help others find a solution.

After the last number is found, there should be 10 possible choices for the first number and 10 for the 2nd. That would yield 100 possible combinations. How did you wittle it down to 8 x 8 = 64? Thank you.

Can’t believe this worked. I went through the process of finding the 12 numbers a few times just to make sure there were no descrepincies and BOOM… Got my lock undone. Who ever developed this and the calculated… Hats off, and a huge thank you.

My number: 38, 35,31.5,28,24.5,21.5,18,14.5,11.5,8,4.5,1.5

Clearly, my last number is 35, but I tried all combination, not anyone works. Need urgent help please!

Hi Jacky,

You may want to try running the calculator for the last number as 34 and if that doesn’t work try 36. This has worked for me with the newer locks. Good luck!

I have an old lock that I’ve not used in some time. The only number that I vaguely remembered being in the combo was 35. After I figured out the last number and put it into the calculator, I tried the first few in the list and then went straight to the ones with 35. I found the combo within six tries! It’s unbelievable that this actually works. Thanks for the clear instructions on how to recover the combo.

AWESOME!!!! now to find all those old locks. LOL

I had a Masterlock that I took from my brother when he came home from Navy boot camp in 1964. I’ve kept it all these years and I never knew what the combo was. Using this method, I got it open in 10 minutes. I should have started on the other end of the page, there were only 5 combinations left when I hit the right one.

Hi, can you please help me with this, I believe I have a unique situation here. At the end I get numbers 6, 16, 26, 36. Which one is the number I should choose?

I KNOW THE FIRST AND LAST NUMBER WHICH ARE BOTH 27. HOW DO I FIND THE MIDDLE NUMBER. NOT A MATH WIZ. I DO KNOW IT’S NOT FAR FROM THE 27, BUT I JUST CAN’T REMEMBER IT. THANKS.

Thank you for the help. I had to cut it off a while back, I needed to get into the shed. Now I have a lock with a key.

What is the algorithm in your calculator?

How are you determining the first two number possibilities?

Found a lock in my closet, haven’t used it in YEARS….used your system….within 1 hour I was able to pop the lock open…Pretty cool!

i need more locked locks.

hot damn it works

took me a while

Mines not working… any extra tips? how many tries does it typically take?

take all simmalar numbers away from the 12 leaves 1 thats the last

number. then goto combo calculater.

took me about 1 hour.g.l.

You sir are a genius…got it to work in 15 trie

I have actually tried this method twice, but I can’t seem to tell if the first set of numbers is a .5 or not. I give up. The lock is an old pink/purple masterlock. 😕

i have tried to find the ending number 5 times by they all end in 2.5, 6, or 9 what am i doing wrong?

The numbers it gave me were

37,34.5,31,27.5,24.5,20,17.5,14.5,10,7,4.5,0

So this should mean that it ends in 31 right?

Yes, that’s right. It should end in 31.

More than likely the 37. The 31 is close to 30, throw out 10, 20, 30

That is the most AWESOME thing. Thanks!

Beautiful! Worked like a charm! Thanks!

i have been trying this method for my lock, but for the first step, the whole numbers left all end in either 6 or 9. what am i doing wrong?

Two points. Make sure you’re turning the dial clockwise and try try to apply a little less tension on the lock. It sounds like the 6 and 9 ending numbers can be ignored.

Hope this helps!

Worked great. Thanks for the technique and the combination calculator.

This works. Very cool!

This is so cool! My new school locker had a lock on it already and I was able to remove it and put on my lock using your technique. The custodian was amazed and said he will use this all the time instead of cutting off a lock. Thanks!!!!

Fantastic! I have a lock I hadn’t used for a couple of years and couldn’t remember the combination for the life of me. Once I figured out the last number and looked at the possibilities, the combination jumped right out at me!

For some reason I get 4 whole numbers and 8 fractions. Is that possible?

I would just try the 4 whole numbers. I don’t think it makes a difference. Good Luck!

I also got 4 whole numbers only

Of those 4 numbers do they all end in the same digit?

It worked!! Thank you so much!! I’ve been racking my brain for weeks on the combo to this lock…

Awesome worked for me thanks

My combination is 31-36-9.

If I were to try this method it would be impossible to find the combination to my lock

This is a great resource! Worked first time – saved me $10 for a new lock – Thanks!

This method does work; however, the 3rd bullet in step 1 should say, “. . . If, on the other hand, the range is in the middle of two numbers say 20.5-21.5, then record 21!, not 20, because 21 is the middle of this range.” Otherwise your whole numbers will always be one number too low! This worked for me . . .

Thanks for finding that. I’ll have it changed. It makes much more sense.

I did it, too on a 900 series. I had that thing for over 35 years since high school. In fact I have 2. One I had the combo for and the other I just cracked. Once I had the list of possible combos, I tried several of the last ones. Then a few I sort of recalled. Then I guessed another and it opened. The last number is NOT the one I always recalled but the method (after doing like 5 times) told me it had to be it. It work. Now I am going to try it on any others I may find or pick up at the swap meet or garage sale. I actually have a use for these things, too. Yes you can crack but seriously you have to be really after my yard tools to do it! THANKS!

Hi Mike,

I like your information on locks.

I also have some information on master combination locks.

I have a video at:

http://www.metacafe.com/watch/862947/find_forgotten_combo/

You can easily get the combination to a lock (if it is open already).

To get it open, you can make a shim from a soda can.

Scott

Thanks for the info, Scott. I have been meaning to make one of those shims. I’ll give it a try and add a post.

I just opened a lock I used on a high school locker 6 years ago- it’s great!

However, at the bottom of the article is the note about moving past 0 for each number; this is somewhat incorrect. The number to pass is not necessarily 0, but the next number in the sequence. For instance 26-04-14, to go correctly from 26 to 4, I pass 0 twice and 4 once, stopping the second time around. Then passing 0 once and stopping on 14 for the final number.

Another interesting characteristic of Master Locks….

Each lock has TWO combinations — they are different and determined by which direction one turns the dial to start the process. Sometimes the alternate combination only has two numbers.

well, it may have worked for you, but i only got the first two digits, leaving me with so many others, oh well, i guess i got work to do…

Some times the sticking points for finding the 3rd number are not exactly on top of a number or between two numbers. In this case:

1. turn clockwise (right) the first of the 12 sticking points from 0

2. continue to turn clockwise to the opposite side of the dial

3. turn counterclockwise (left) back to the first sticking point from 0

4. pull up on the lock and turn the dial left and right in the small sticking area and write down the exact range. (e.g. 2.75-3.5)

5. repeat this 4 more times for the numbers 10 more from each other. (e.g. 3, 13, 23, 33)

6. now do steps 1-5 for the second sticking point past zero

7. do the steps again for the third point past zero.

Got it in the FIRST tried it worked! 🙂 and i hadn’t used my lock in almost a year i had no idea what the combination was

I just tried this on a Sphero serial 8000xxx, and none of the combinations worked. My last number is 37. At first, on my first try with 1-3-37, the shackle popped open, but ever since, I haven’t been able to open it with any of the other combos. Any ideas?

I’m not sure, but the 1 or 3 seem too close together to be a valid 1st and 2nd number. Try 1 and 5 or 0 and 4 and see if that works. Good Luck!

Tried on on a Hardened Masterlock serial 911*** and it worked just dandy. Takes a bit to figure out the whole tension / wiggle technique so you get the right numbers but it worked for me.

The problem that some of you may be having with the hardened locks is that Masterlock changed their tumbler design for a lot of the locks that have serial numbers beginning with 800. If you check the wikihow article on how to crack a combo lock, it gives some tips as to what might be going wrong if this applies to your lock.

Nice. Got it on the 13th attempt. (I worked the possible combinations list backwards) The hardest step was finding the stopping points. I’ve tried this on 2 other locks now, that I did know the combination to, and it worked. Thanks.

Thank you so much. Because of this, I was able to open my High School lock from ’91 and give it to my daughter to use for one of her school lockers!

I got twelve numbers, but five are .5s and seven are whole. All the .5s end in the same number except for one, which, using the method described above for the .5s instead of the whole numbers would give me a last number of 1.5. That doesn’t work with the math unless I treat it as either a two or a one, and that leaves me with twice as many combinations to try. Any other options?

UPDATE: I exhausted all possibilities for 1 and 2 as the third number with no luck. 8.5 is the loosest of the stopping points, but, once again, I’ve got a fraction instead of a whole number. I guess I’ll try 8 and 9 but I’m wondering if I read the stopping points as the wrong numbers.

Thanks, this worked great. I got the list of 64 combos and recognized what the combo was. So I got it on the first try. 🙂 Lucky me!!

got lucky! 1st try woohoo!!! yyeaahh! i tried soo many sites but this is the only 1 that worked 4 me i think it is great!!!!and now i dont have to blow a ton of money (well kind of a ton) on a new lock! you go girl (or guy, idk) 🙂

Wow … it really works. I have a master lock from high school sitting around in a toolbox for 25 year. I mixed some of the number up the first time, but got it straight the second time and found the last number was ‘8’ … printed out the list of possible combinations … picked a column that looked right and bingo! opened up on the very first try. Amazing. Thanks!

Doesn’t work for me. I get six .5’s and six whole numbers:

39, 36, 29, 19, 16, 9. Four 9’s and two 6’s. Any ideas?

OK. So I had four 9’s and 2 6’s. I picked one of the two 6’s and started there. Sure enough, it was the correct final number and I got the lock open. I guess if I had tried all 64 I would have then tried the other 6 as the final number.

So, FYI for others who have this problem. Try both of the two “unique” ending numbers.

Awesome! Masterlock’s web site wants you to fill out a form, photocopy your lock, get the form Notarized, and mail it in for a 4-6 week turnaround. I’ve had this lock for years and finally lost the little code sticker that came with it. I had a vague memory of the code, and that the first and third numbers were similar. I ran through the dial twice to get the list of possible numbers, found the most likely last number (I ended up with 4 and relied on my memory), and got it open on the first try. THANK YOU!!! Now, do I bother using this for the lockerroom because it was so easy to crack? …yea… My clothes aren’t that valuable! woo hoo!

Does this work for built in locks with numbers from 0-49 instead of 0-39

Not sure what to do. I had 2 locks that I bought at the same time, and their serials are close together. I was able to use this method to open one, but there’s no clear solution to the other. I’ve gone over the sticking points about 6 times.

1.5, 4.5, 8, 11.5, 14.5, 18, 21.5, 24.5, 28, 31.5, 34.5, 38

That makes only 4 whole-numbers (8, 18, 28, 38).

Any ideas??

I had the same problem. What seemed to make sense, was that the “sloppiest” whole number was the ending number. If you don’f feel like testing all of them again, then write down the ranges instead of the average each time. My last turned out to be 6, with a range of 5 – 7. Whereas the other whole numbers had ranges of 35.5 – 36.5. Hope that helps!

I originally learned this back in 1964. It was shown to be by an Eighth grader. He could actually open one in less than 10 seconds is looking at the lock and about 30 seconds behind his back. I since forgot quite how to do it so I decided to look online and here it was. There is another way to crack the lock if the lock is not on something and that is throw it down hard on its shackle, it sometimes will snap open. This does not destroy the lock, but you still wont have the combo.

I only get 10 sticking point ranges on an American lock. 4, 12, 36 are the only whole numbers. It seems like this should be an easier algorithm, no? Any ideas?

Totally Works… had 2 locks collecting dust for over 5 years in my drawer and finally founds their combination with this trick… thanks a lot!

It didn’t work on my MasterLock model 1504 (purchased on 2009). Apparently this model uses another algorithm

This was amazing. After looking at the possible combinations, I got it in one try!

You Rock!

This helped me solve a pad lock my dad forgot the code to in boot camp 19 years Ago!

I have tried this about 30 times. I also have had other people try it. We all come up with the same numbers. 0, 3.5, 6.5, 10, 13.5, 16.5, 20, 23.5, 26.5, 30, 34.5, 36.5. I can only get 4 whole numbers and they all have the same last digit. Any suggestions on how to get the combination?

Thank you. Thank You. THANK YOU! I recovered the combination to a Master Lock lock that I have owned since high school (I’m now a grandfather), but could not open.

Thanks to all of you for your posts. My lock had 8 fractional and 4 whole numbers. After trying the fractionals as possible last numbers, I re-read the posts more closely. I looked for the loosest whole number which was the first 8 in the series of 8s. I also noticed through all this trial and error, when the shackle was pulled up, my lock would click (hit metal) consistently clockwise on 14 and counterclockwise on 12. For kicks, I went through the combos with 14 as the middle number and found the combo of 32-14-8. For anyone looking for serial number 905460, this is the combo.

Thank you so much for this post! I just cracked a combo for a lock that’s been stuck on a bag for 5 years!!

I have a very old Master lock for a gym (the kind with a key slot in back and the combo dial on the front).

My stepbrother would go around the school on the last couple of days and collect up all of these locks, from trashcans, from open lockers, you know what a jr. high school looks like at the end of the year.

For fun, he would just go through the combos from the start 0-0-0 and find the combo. He got good at it, I mean REALLY good he could pick up a cold lock and in 5 to 10 minutes it was open. I think his brain got the algorithm in his head.

At any rate, he always had a box of locks if anyone needed one. He gave me one and it has been really beat up, dented, misused, and abused. The combination for it is 0-10-0.

I had forgotten the combo. So I tried the long way and it wouldn’t give five whole numbers, it always gives six, after playing around with it for the weekend I still can’t open it, should I just junk it or is there a trick of some sort? I got the lock in 1973. It don’t owe me now’t, but I don’t want to throw something away if it will work.

To clarify for the readers and what worked for me. The fractional numbers are the important numbers. Average the 5 fractional numbers. Once averaged, 4 of the 5 numbers will end with the same number. The one that is different is the last number of the combination lock. Then use the calculator.

Wow. Just cracked the combo for 2 locks that were in cold storage. Thanks so much.

This is way cool. I had a little trouble getting the feel of determining the last number. I had a false positive of the four numbers with the same last digit, which cost me some time. Then realized that I was had turned the dial counter-clockwise rather than clockwise to find the third number. I recall seeing another website that said clockwise, but it doesn’t matter. Just make sure that you turn the dial counter-clockwise to find the last number.

Now that I’ve recovered my combo, it occurs to me that my lock is still as useless as it was when it was locked without the combo as are all my other Master combo locks. Anyone can crack these locks, so what’s the point of using them to secure anything of value.

Has anyone seen a response from Master Lock regarding this flawed design. I didn’t see anything on their website. What a disappointment. I’ll never buy one of these locks again.

Meant to write in my previous post: I recall seeing another website that said counter-clockwise, but it doesn’t matter.

I’ve been trying to figure out my combo for two days by doing this method with my own math. Finally I found your chart and I got it open! (Of course my combo was the second to last on the list…) Needless to say I have sore fingers.

The computer calculated combination sets generated for “last number” 29 do not give the combination 15 20 29- which is what my 800XXXX MASTER is??? Luckily I found the original leaflet and combination that came with my lock!! (after going aroundandaroundandaround…)

My guess is the last number of 28 will open this lock. When the last number is odd I always take the lower even number to make this work.

You have brought up a good point concerning ending odd numbers and I will investigate further.

This method worked great for the first lock I tried but the second lock have a last odd number and I am having no luck. I tried all the combo’s on the chart twice and then read your post. I rounded down to 30 from 31 and recalculated the chart and tried all those numbers with no luck. A couple of questions:

1) do you mean to round down and then recalculate the chart? or calculate the chart with the odd last number and then round down just that number from each of the chart numbers?

2) When spinning the combo, pass 0 twice first spin clockwise, pass 0 once counter-clockwise second turn.

I had a line of combo’s from the chart with 0 in the middle. I tried both landing on 0 the second turn and passing zero twice and landing on the third zero. Which is correct?

Thanks for the great info!!

There’s also a new iPhone App ‘LockGenie’ which helps with this and gives you extra mobility.

http://itunes.com/apps/lockgenie

Didn’t work for me but will try again.

I can’t believe that it actually worked. When the shackle came unlocked, I sat there staring at it in disbelief. So I tried it again and it worked. thanks a lot again. I will be referring back to this site for all my master lock combination needs. Oh, and by the way, it does work for hardened locks.

c0rm3n put it best when asking:

“what is the algo used to eliminate the band of numbers going diagonally?”

Posted by c0rm3n | August 27, 2009, 11:44 pm

I’m not into reading code (and not for lack of trying. Specifically the source you provided.)

The “long” method popularized on all the other websites instructs composing the list of 100 possible first and middle numbers. In the field, I’ve tried a few that I suspected couldn’t work after trying them because of the awkward placement of certain number pairs and the mechanical feeling that the dial “went too far in the other direction.”

What is the layman’s-written-out-in-plain-language mathematical process for narrowing down this list to 72 as I understand it to do? What is the criteria for eliminating some of the numbers off the bloated “100 list?”

By the way, awesome site and helpful contribution!

It was very hard for me to get the last number but I did find my combination. THANK YOU!!

It works. Most of my numbers stop between numbers, not on a number. So it was a little tricky. The last number for me, which is 6, actually stopped between 5 and 7. I did remember my combination had a 6 or a 2 in it so it took me only 3 tries to figure out from there.

In responce to hardened lock question ..I had a hardened lock that this method didn’t work for because all of my whole numbers ended in 4. I looked for the loosest one and began trying on them and it did open. So look for the loosest whole number to get your last number.

^^ FTW! I had 4 0’s and no other whole numbers, the loosest one was the third number.

Wow, I wish I’d read this earlier. I convinced myself that a couple of the half numbers were possibly whole… now my hands are numb from all the futility, but at least I’ve got it!

Huh, my last number was also 30.

I love you so much right now. I had 4 whole numbers, and 8 half numbers. I was trying to figure out which of my halves was wrong for soooo long before I saw your comment. I have a hardened lock also. Btw, my last and loosest number was also 30.

thank you very much for this, I’ve been trying for hours to figure my combination out when I finally decided to look up help. surprisingly enough, the combination was the first on the chart (:

I’m really glad it helped, Jostie. Thanks for your comment.

what is the algo used to eliminate the band of numbers going diagonally?

The mechanics of these locks are sloppy enough that adjacent numbers are valid combinations. For example, a combination of 9-27-12 is the same as 10-27-12.

I have posted the source code for your perusal. Does this answer your question?

Source code in PHP

“what is the algo used to eliminate the band of numbers going diagonally?”

Posted by c0rm3n | August 27, 2009, 11:44 pm

What happens is that sequential numbers which are close together are eliminated. This is because the design of these combo locks gives fairly large tolerances when entering a combination. It seems to be plus or minus 1 number giving you a range of about 3. Because of this, the possible combinations cannot contain sequential numbers that are only 2 values apart.

A combination of 10-12-26 would be invalid because once you enter the 10, the 12 will just fall into place, making the entry of the combination very awkward and difficult.

A combination of 10-32-34 would also be invalid for the same reason, even though the two numbers that are too close are the second and third. This flaw exist across the entire combination.

The algo that eliminates the diagonal numbers simply looks at the first two numbers in the combination and if they are only two numbers apart, that combination is eliminated.

This is the same reason why there is a horizontal band of numbers missing. All of those combinations had second and third numbers that were only 2 numbers apart, and thus were invalid combinations.

Here’s exactly how those other numbers are eliminated. There are two rules that cut the possible combos from 100 to 64:

Rule 1: The second number cannot be 2 more or 2 less than the third number.

Ex: Combos that wouldn’t work:

2-36-34 | 36 is 2 more than 34.

2-32-34 | 32 is 2 less than 34.

22-0-38 | 0 is 2 “more” than 38.

22-0-2 | 0 is 2 less than 2.

Rule 2: The first number cannot be 2 or 6 more than the second number.

Ex: Combos that wouldn’t work:

18-16-34 | 18 is 2 more than 16

18-12-34 | 18 is 6 more than 12

0-38-4 | 0 is 2 “more” than 38

0-34-4 | 0 is 6 “more” than 34

Keep in mind, those zeros are can be sneaky little bastards! Remember that you’re dealing with a wheel here.

If you follow these rules, you can crack the combo without a computer! You may need some extra paper though, at least if you’re like me and need to write all the combos out. 😀

Does this still work if the numbers go from 0 to 49?

can you explain why the second rule works?

Doesn’t work for Hardened locks. How about a tutorial for them?

Worked for me, too! you don’t have to do all that stuff for the last number; pull down hard and turn; dial will lock up firm on the last number. Then go to Calculator. Start with the more likely groups (different first and last numbers. I did it in 19 trys. 🙂

Please not that two of the numbers can be the same. I read on various website that this is not the case and it was giving up on cracking my old lock, but thought I’ll give it a try and my combination turned out to be 26-32-26.

I have an anti-shim combo that has the combination 11-37-11

Worked for me:-)

This is great. I’m going to try this. I have a lock that I lost the combination for, although I remember one (maybe even two) of the numbers. This will help me to be able to get the combo quickly.

Clearly there is a hidden culture that frequents web sites like this. Now you two have joined that culture. Linda, what have you done?

This is a brilliant site, to be sure, but now it’s clear who stole Pee Wee’s bike.

Come to think of it, I’m missing some underwear from my locker at the gym. You wouldn’t happen to know the whereabouts of a certain black lace thong, would you?

When I was a young teen, I bought a 3 speed bike with my own money. While at ta park, I locked it to a tree. When I returned, the lock was gone, but the bike was still there. I thought it was some wise ass kid that did it, now I know that it was a brillant adult like you practicing. Thanks for clearing that up! I am going to send my son to this site!

Once said, “knowledge is a form of power” but really this upsets you? A theif will take a hammer & smash part of the lock or use a cloth, well… Thank you, now I can use that old lock I have again. Something about keeping honest people, honest. Ching Chow..