How to crack a master combination lock

Finding the 'First Locked Position'

1. Set the dial to 0.
2. Apply full pressure upward on the shackle as if trying to open it.
3. Rotate dial to the left (towards 10) hard until the dial gets locked.
4. Notice how the dial is locked into a small groove. If you're directly between two digits such as 3 and 4, release the shackle and turn the dial left further until you're into the next locked groove. However, if the dial is between two half digits (e.g., 2.5 and 3.5), then enter the digit in-between (e.g., 3) into First Locked Position in the calculator below.

Finding the 'Second Locked Position'

1. Do all of the above again until you find the second digit below 11 that is between two half digits (e.g., 5.5 and 6.5), and enter the whole number (e.g., 7) into Second Locked Position in the calculator below.

Finding the 'Resistant Location'

1. Apply half as much pressure to the shackle so that you can turn the dial.
2. Rotate dial to the right until you feel resistance. Rotate the dial to the right several more times to ensure you're feeling resistance at the same exact location.
3. Enter this number into Resistant Location. If the resistance begins at a half number, such as 14.5, enter 14.5.

Inputting the Numbers into My Calculator

1. Make sure all three numbers are entered into the calculator at the top of this page, then click Find Combos. We now have 20 possible combos, but we'll reduce this further. Keep reading!

Finding the Right 'Third Digit'

1. Set the dial to the first possibility for the Third Digit.
2. Apply full pressure upward on the shackle as if trying to open it.
3. Turn the dial and note how much give there is.
4. Loosen the shackle and set the dial to the second possibility for the Third Digit.
5. Apply full pressure upward on the shackle as if trying to open it.
6. If there is more give on the second digit, click the second digit in the calculator above. Otherwise, click the first digit.

Testing Out the 8 Combinations on Your Lock

1. You are left with 8 possible combinations. Test them all until one works with the standard instructions below.

Standard Instructions for Opening a Combination Lock

1. Turn right three times. Stop at First Digit.
2. Turn left one full turn passing 1st number and stop at Second Digit.
3. Turn right and stop at Third Digit. Pull shackle. Profit.

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Hi Samy,

Same as others here, I have an older lock from maybe 5-6 years ago, serial on bottom reads 1211CF. Same trouble. The dial locks at 2-3, so I skip. The first locked position then is 5.5 and 6.5. Next, it locks between 9 and 9.8. Then the next locked position is 12.2 and 13.1. Next is 15.5 and 16.5. Kicker here is that I do know the combination on this lock, as it was never used and still has the sticker. Happy to work with you on this. Would like to help amend your code to make it universal if possible. Standing by.

I'd love to know the math too.. I had to combine this with the "in 100 tries or less" method. The 3rd number was wrong, but easily found manually, the 1st number seems to be generated based on the resistance number, and even though it worked it wasn't the right number (only 1 digit off so maybe human error or glitch in the matrix) but regardless, 1 digit discrepancy still works in most cases. And my 2nd number was also only 1 digit off.. But I could generate the right digit using the "100" algorithm.. This all makes me REALLY want this formula, because I feel like with a little tweaks you can have a definitive 3rd, 1st, and maybe narrow down the 2nd. It all makes me wanna grab a few more locks from the store to test some theories and equations

If you used your formula, and compared your results with a well known matrix for master, one could perfect this

I only have one number between 0 and 11.
I got a 8 and a 11. So I wasn't able to use your formula.

Since it is a rotary dial I decide to try between 30 and 0 and I was able to get 35 and 38 with the resistance at 38.

I added 10 in modulus 40 to each number and input the number into the calculator.

The calculated result was then reconverted to get the correct dial number and on the second trial the lock opened.

My lock was 3,33 and 15

Amazing it works!

But you need to change your calculator formula if somebody like me doesn't have two numbers between 0 and 11 (exclusive).

Hi Samy, first of all, I got my lock open - so thanks! It did take me a few more than eight tries though so I thought I'd give some feedback in case you're interested or someone else finds it helpful.

1. My resistant location is around 19 which the calculator translates into a first digit of 24. However, my first digit is 25. In fact, the resistant location is a little over 19, but closer to 19 than 19.5. I estimate it's about 19.15, which does give 25. Instead of rounding up and adding 5, maybe add the offset (5.85 for me) and then round to the nearest number?

1. My locking positions are 1, 4.5, 8. I discount the 4.5 because it's a range between two whole numbers (4-5) and enter 1 and 8 and get a last digit of 1 or 21 (or 8 and 28 depending on whether the first digit is right). But my last digit is 25! The locking range around 25 is a bit more than at 4-5, so that it does cross 25 (24.2-25.4). So it's correct to discount a range between two whole numbers, but this discounts only that particular range, 4-5, but not also 14-15, etc. I got it by the traditional advice of writing down all 12 midpoints, then discounting the .5s and the whole numbers ending in the same digit.

That's a load of nonsense. How do you conclude that "if something doesn't work on a how-to" it's probably the fault of the user? Do you see the dozens of people who have said it isn't working?

It's not working for me, either. But I don't suspect Samy is going to reimburse us all for the lost time. It's nice that he's doing this kind of thing -- he's a good hacker. I like his little programmed device, too. But if he hasn't checked with strong confidence, he shouldn't release it. He needs to do more work before publishing unreliable reports, and it's irresponsible to publish something like this without checking on all of the problems and making revisions. He appears to have started trying a year ago, then he gave up. Instead of unpublishing this, he's left it up for thousands to try and fail at.

Sammy I am truly amazed by how smart you are . I looked into your other stuff like phreaked out and your other articles . I want to start learning about these things . I'm somewhat tech savy but nothing like your status . I'm not asking to learn how to hack because I know it's not as simple as that . It's a bit more specific it looks like . Where do I start ? How long did it take you to be as wise as you are with all your stuff ? I mean, you built your own freakin machine and for that I envy you . Any tips , guides, or words of wisdom would be greatly appreciated!

I have 2 locks I found in a storage box that I had lost the combination to. My first try with this hack worked immediately. The second lock, was a bit more challenging. I thought 0 was one of my locked numbers, but no! I also missed the .5 on my resistance number. This gave me a 40 as a possible third number. Ha! Impossible on this lock.

I just kept at it until I had the accurate numbers to input in the calculator.

So my advice, if you don't get a solution, is go back to square one and start over. Try adding .5 to your third number. (Ex. 13.5)

Good luck folks!

For anyone who has struggled with this walk through, also watch this video - the first number is the "sticky" number +4 or 5 or 6, so the real trouble is which way to turn to find the sticky number - TURN COUNTERCLOCKWISE, if you don't want to lose your mind. So here's the link, youtube.com/watch?v=wdkf1Z_Bmfw

and everything else works. Create a list of ~ 4 possible starting numbers, 2 possible final numbers, and 8 middle numbers based off of your final number (remainder 4, +2). This is the surefire way to crack one of these locks. If this doesn't work, make sure that you find the first number by TURNING COUNTERCLOCKWISE!

Typed a whole response, but this pos website gave some stupid Ajax error and poof it was all gone. Can't people code stuff anymore. For those that can't get it to work for their lock, there is a reason. The author got well out over his skis and assumed all master lock 1500's are the same.....news flash they aren't. This won't work for many like those with serial numbers starting with 909, 910 etc. The resistant number doesn't go in the first position for starters, and you dont add 5. The 3rd number is found by finding the anomaly to the 3 detents from 1 to 11 and adding 10 3 times and looking for the one that's off. The missing number is gained by brute force or finding other smaller resistant numbers.

As for Brute force, don't need to try all 40 numbers, every other number works fine (20x max), as masterlocks aren't precision instruments. As for clarification on finding the anomaly(3rd number) , you don't need a calculator....just do this. Go to zero, find the first detent (between 0-11), lets say it's exactly 2-3, add 10, go to 12-13, is it exactly between 12 and 13 like it was for 2-3, if so add 10 again (22-23) same question up to 33-34. Go to the next detent, maybe this is 4 3/4 to 5 3/4, add 10, is it between 14 3/4 and 15 3/4 on and on till you find something like 34 1/4 to 15 3/4, and there is your anomaly. Write it down, as that is your 3rd number of the combo. Beware, many are quite subtle. Another hint, look for other resistance number other than your predominate number as they will be likely candidates for success. In finding your missing number. Good luck

As for Brute force, don't need to try all 40 numbers, every other number works fine (20x max), as masterlocks aren't precision instruments. As for clarification on finding the anomaly(3rd number) , you don't need a calculator....just do this. Go to zero, find the first detent (between 0-11), lets say it's exactly 2-3, add 10, go to 12-13, is it exactly between 12 and 13 like it was for 2-3, if so add 10 again (22-23) same question up to 33-34. Go to the next detent, maybe this is 4 3/4 to 5 3/4, add 10, is it between 14 3/4 and 15 3/4 on and on till you find something like 34 1/4 to 15 3/4, and there is your anomaly. Write it down, as that is your 3rd number of the combo. Beware, many are quite subtle. Another hint, look for other resistance number other than your predominate number as they will be likely candidates for success. In finding your missing number. Good luck

Mister Lee, your method works for finding the last number, and is the simplest yet, thank you!

The 100 method also works, but takes a little longer

Strangely, I have a lock where pulling half way, the sticky number was consistently at 38, and the first number was not 3 as the formula on this page suggests (add 5 to the resistance number), it was the second number that was 3!

Anyway, the 100 method works (I got it on the 71st attempt in my case). It opened even though the first two numbers were off by one--which I verified by trying above and below the numbers that originally opened it. It seems that master locks are lenient by one number either way for each position.

The method on this page ended up with the first two numbers being reversed and the third number being wrong.

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