(13 votes, average: 4.38 out of 5)
Loading ...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 would take at most 22 days of full-time trying. 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.
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 20. 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.
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..
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 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.
Worked for me:-)
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.
Doesn’t work for Hardened locks. How about a tutorial for them?
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?
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.
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.
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.
It was very hard for me to get the last number but I did find my combination. THANK YOU!!
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!
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.
Didn’t work for me but will try again.
There’s also a new iPhone App ‘LockGenie’ which helps with this and gives you extra mobility.
http://itunes.com/apps/lockgenie
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!!
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.
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.
Wow. Just cracked the combo for 2 locks that were in cold storage. Thanks so much.
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.
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.
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!!
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. 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.
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?
You Rock!
This helped me solve a pad lock my dad forgot the code to in boot camp 19 years Ago!
This was amazing. After looking at the possible combinations, I got it in one try!
It didn’t work on my MasterLock model 1504 (purchased on 2009). Apparently this model uses another algorithm
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!
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?
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.
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??
Does this work for built in locks with numbers from 0-49 instead of 0-39
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!
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.
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!
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)
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!!