Crack Any Master Combination Lock in 8 Tries or Less Using This Calculator

Master Lock combination padlocks have been known to be vulnerable to an attack that reduces their 64,000 possible combinations down to 100. I've devised a new attack for cracking any Master combo lock that simplifies the process and reduces the amount of work down to only 8 combinations.

• Don't Miss: Behind the Hack: How I Discovered the 8-Try Exploit

Use this calculator in conjunction with the instructions below to find the 8 possible combinations for your Master combo lock.

Watch the video for the full details, deconstruction, and a sneak peak at my robotic combo lock-cracking device. Written steps can be found below.

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'

5. 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'

6. Apply half as much pressure to the shackle so that you can turn the dial.
7. 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.
8. 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

9. 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'

10. Set the dial to the first possibility for the Third Digit.
11. Apply full pressure upward on the shackle as if trying to open it.
12. Turn the dial and note how much give there is.
13. Loosen the shackle and set the dial to the second possibility for the Third Digit.
14. Apply full pressure upward on the shackle as if trying to open it.
15. 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

16. 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.