How To Crack A Master Lock

How to Crack a Master Combination Lock

Within the art of lock picking lies the infamous combination lock, a device immune to our tension wrenches, lock picks, and standard methods of lock picking. While there are still many other ways to bypass a combination padlock, including the use of a shim, bolt cutters, locksmiths, or even a blowtorch, none are quite as elegant and non-destructive as old school combination cracking.

A standard 40 digit Master Lock has 64,000 combinations which would take the average human about 180 hours to crack by using random combinations. This guide will aid you in reducing that absurd number to only 80 combinations and instruct you on how to crack a Master Lock in 10 simple steps.

1. Determine Your Model Of Master Lock:

Before we spend the time required learning how to crack a combination lock, it’s important that we first determine if this method of cracking will work on your model of lock. Some Master Locks require additional or different procedures to crack as they use different combination algorithms.

The model number of your Master Lock can be found on the back of the lock. If by chance your lock’s model number begins with 800 or 908,  this method of combination cracking may not work. However, many people have had success cracking 800XXX model Master Locks using this method, but there is no guarantee.

2. Clear The Lock

The first step in picking any lock is to set a standard starting point. In the case of a Master Lock we simply clear the lock. This is accomplished by rotating the dial, at minimum, three times past the zero mark in the clockwise (right) direction. Additionally, be sure to stop the rotation at the zero mark as well.

3. Placing Tension On The Shackle

Now that the lock has been cleared and is set at zero, our first objective, which will seem backwards, is to find the third number in our combination. Begin by applying a tense pulling force on the shackle of the padlock. A great method of doing this is to grasp the lock in one hand while using a finger to push upward on the shackle.

Parts of a Master Lock

While maintaining this upward pressure on the shackle, begin to rotate the dial slowly in the counterclockwise (left) direction. Note here that there may be chance the dial will be stuck on the zero mark while force is applied to the shackle and will not allow you to rotate it. If this is the case, release the force on the shackle and rotate the dial one or two numbers counterclockwise. Reapply the upward pressure on the shackle and once again try to rotate the dial counterclockwise.

4. Finding The First Sticking Point

While rotating the dial of the lock in the counterclockwise direction, you will shortly come to a point where it will jam and no longer allow you to freely rotate it. The dial will be stuck in a rut between two numbers. You should be able to turn the dial slightly in the clockwise (right) direction and back again while still holding pressure on the shackle. This is our first “sticking range.” Write down both stopping points in this rut. For example the counterclockwise (left) stopping point could be 8, while the clockwise (right) stopping point could be 6. In this example our sticking range would be 6 to 8. Next we have to find the “sticking point.” This is done by simply taking the middle number of our sticking range. In our example this would be 7.

Be aware when finding your sticking range that the dial can also stop between numbers or, that is, halfway. An example of this would be when turning the dial in the counterclockwise direction to find your stopping point and it instead stops between 8 and 9. Your counterclockwise stopping point would then be 8.5. In addition, when you rotate the dial in the clockwise position, it stops between 6 and 7 giving you a stopping point of 6.5. The resulting sticking range would be 6.5 to 8.5 and our sticking point would be 7.5.

Master Lock Sticking Range Half Numbers

5. Finding The Second Sticking Point

Now that we have found our first sticking point, we can move on to the second sticking point. Release the upward tension on the shackle and rotate the dial counterclockwise until you are just past the higher number of you last sticking range. For example if your previous sticking range was 6 to 8, rotate the dial to 9.

Next reapply the upward tension on the shackle and just as before, turn the dial in the counterclockwise direction until it once again jams. Take note of this counterclockwise stopping point and, with tension still applied, rotate the dial clockwise until it stops once more, giving you your clockwise stopping point.  Once again, record the sticking range and determine the middle number to find the sticking point.

6. Finding The Remaining Sticking Points

All 12 Sticking PointsWe now have 2 of the 12 sticking points we need to crack the third number of our combination. Repeat the following steps of rotating the dial in the counterclockwise direction and finding the sticking points until you have 12 numbers recorded.  Below is an example of the sticking ranges and sticking numbers I collected while cracking my Master Lock.


7. Cracking The Third Number

5 Remaining NumbersIf you take a look at the sticking points you have recorded, you might notice that there are seven fractions and five whole numbers.  Cross out all of the fractions leaving only the five whole numbers. In our case we are left with 0, 10, 20, 27, and 30.

If you did the steps above correctly you will notice that all of your remaining numbers end with the same digit, except for one. This oddball is our lucky winner as it is the third number in our combination. For example, my numbers are 0, 10, 20, 27, and 30. All of which end with 0, with the exception of 27. The third number of my combination is therefore 27Third Number To Master Combination Lock.


8. Finding The First Number Of The Combination

Now that we have cracked the third number of our combination, we can determine the ten possibilities regarding the first number of our combination. The first step is to take the newly found third number of our combination and divide it by four.  In my case,  27/4.


Of this new resulting number, we are only concerned with remainder, or that is the decimal point. Write this number down. In my case I resulted with 6, making my remainder 3. Also note that with these locks, the remainder will always be either 0, 1, 2, or 3.

Now that we have our remainder, it’s time to find our ten possibilities for the first number in our combination. Begin by adding four to the remainder and write it down. Then again add four to that result and continue adding four to each resulting number until you have a total of ten numbers. In doing this, your tenth and largest number should be a number available on the dial. One of these ten resulting numbers is the first number in our combination. In my case the remainder was 3 and as I continuously add four I result with the numbers 3. 7, 11, 15, 19, 23, 27, 31, 35, 39. These our my ten possibilities, one of which is the first number in my combination.

Be aware, if your lock is of the 800XXX models, this set of numbers could possibly be for the second number in your combination instead of the first number.

9. Finding The Second Number Of The Combination

To find the second number in our combination we again need to look at the remainder we used in the previous step. If your remainder was 0 or 1, then add two to it. If your remainder was 2 or 3, then subject two from it. Take this new number and add four to it.

Just as we did in the previous step, continue to add four to the resultant until you again have ten resulting numbers. In my case the remainder was 3, so I  would subtract 2 giving me a new number of 1. I then continuously add four to my new number giving me the following 1, 5, 9, 13, 17, 21, 25, 29, 33, 37. We can narrow these ten numbers down slightly more by removing any number within two of our third combination number. In this case, because my third number was 27 I can remove 25 and 29 leaving me with 1, 5, 9, 13, 17, 21, 33, 37. These are my eight possibilities, one of which is the second number in my combination.

Once again,  if your lock is of the 800XXX models, this set of numbers could possibly be for the first number in your combination instead of the second number.

10. Cracking The Combination

We now have all the possible first and second numbers for our combination and have for certain our third number. We have taken a possible 64,000 combinations and diminished it to 80 possible combinations. The next step is to simple hash out all the possible combinations until one works. Lets start by entering our first possible combination. In my case it would be 3 – 1 – 27.

First, you must again clear the lock by rotating the dial at minimum three times in the clockwise direction. Then while continuing to rotate the dial clockwise, enter your first number. Mine is 3. Next rotate the dial counterclockwise past your second number and continue to rotate it until you land on that number again. Mine is 1, so I rotate past 1 and keep turning until I once again land on 1. Finally rotate the dial once more clockwise to your third number. In my case it was 27. It is very likely that your first combination wont work. But continue to clear the lock and enter every possible combination until find those magic numbers. My combination ended up being 19 – 5 – 27 and took me roughly 15 minutes to crack.

You now know how to crack a Master Lock!

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What if your master lock does not have a model number on the back?


Awesome my son lost the combo for his lock so I followed your steps and formula to crack his combo on my 5 set of numbers after trying the pressure methods without success. I did get the first number from the pressure method which help in the end as I used that and the 3rd number from your formula. Great stuff thankyou it was such a shock when it snapped open.

Truan Leiker

Is there any known method of cracking a 908 Master Lock?


Wow! This method actually works! I was beginning to give up hope when I forgot my bike combination lock. But you proved me wrong! Thanks for giving me my bike back!


This Worked!!! I was so sure I half remembered my combo and would recognize it. I didn’t remember it at all but luckily it was the 4th one I tried. What’s weird is I remember it coming with a combo that was all multiples of 5 but it was hard to open with that combo and it’s really all numbers ending in 4 according to this method.

now I have to decide if I want to use a lock that’s so easy to crack >_<


Oof…it worked for me too, but on the last of the 10 first numbers. My fingers hurt after plugging in 72 combinations! TY for the method…I love the internet!


I have a model 800 master lock what methods should I use to crack one of those.


Several sites tell this same story and claim to work with any master combo lock. Except that the instructions do not work with letter locks. Master’s letter locks have only 20 positions and do not use all of the letters. Do you have instructions that are written for these locks?

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