# Master lock “picking”

Here’s any easy method for backing out the combination of a Master Lock. In a perfect world there would be 64,000 possible lock combinations (403). The construction of the lock prevents this from happening: sloppiness in the dial and the numbers are not mathematically independent. First step is to determine the last number in the sequence. You can then use that number to determine the other possible numbers in the combination. You will end up with about 100 combinations to try, but that’s far better than having to throw the lock out which I’m sure would happen if you had to try 64,000.

UPDATE: x04d sent in a video demo (DivX) (dead link) of how to open a lock in 2 sec. using a padlock shim.

UPDATE: The linked video above has long been dead. Check out our more recent Master lock post for an embedded shimming video

## 107 thoughts on “Master lock “picking””

1. Sirlancelot says:

I think that just taking the whole entire lock apart with a pair of normal plyers (cat cut metal) and maybe a screw driver is much more fun, unless its ur own lock… I can take apart a lock in about 10-15 minutes…

2. Sirlancelot says:

I think that just taking the whole entire lock apart with a pair of normal plyers (cat cut metal) and maybe a screw driver is much more fun, unless its ur own lock… I can take apart a lock in about 10-15 minutes…

3. Tim says:

I used to open the combo locks with a shoe string, rapping it twice around the dial and then pulling the shoestring up and down verying your strokes up and down till it opened! Anyone heard of opening them that way? It does work!

4. md says:

my gf got my old locker. she gave the combo and i saw that its the only 6 numbers different that mine was. say my combo was 10-10-10. hers is 4-4-4. we tried this on a bunch of lockers my buds had lst year and they all open with 6 less than there old combos. i dont know if this is a pattern. this is a new school with new locks with zephyr lock on the knob. so i don’t think its cause there old or busted or anything. is evry lock like this? -md

5. matthew says:

I could REALLY use your help!

My trusted Dudley lock, which I have used for over 10 years, seems to be stuck. The locking portion of the U seems to be stuck: it won’t pull up, and it won’t go back down into the rest of the lock. The dial won’t move, either… although if I jiggle the U, i can get it to move a little bit (sometimes).

Any ideas? I’d hate to get a new one, since I’ve used this same combinations forever!

Thanks,
Matt

6. Doug says:

Hey I forgot the combination to my master lock and would like to see if you any way on cracking it. It is a Master Lock 175 four digit combo. Thanks

7. steve says:

hey i have the serial number for my lock, which is the ones they use at school in the locker rooms, its a masterlock with the u shape thing. can someone give me the combo?

8. Kyle says:

Hey, does anyone know how to crack a Dudley lock? I really need to get into my locker as all my stuffs there, but I can’t get in it. My school knows that Masterlocks are easy to get into, so they all have Dudley. I really need in my locker. If someone knows how to, Can you please email me at Chaos_is_fun@hotmail.com ?

Thanks.

9. ummmmm yea says:

ox4d yea the little clip on how to open a master combination lock in 2 sec. dosnt work so could you plz add a comment on how to open one in 2 sec. thnks

10. lock dock says:

does any one no if it is possible to impress a key for a master combination lock?
and what size key would you need to impress the key hole on it?

if you no how plz add me to ur account or send me a email on how to do that thx

lol565lol@hotmail.com

11. Mary says:

I have a Master Luggage lock that is stuck locked. I don’t remember the combination of THREE numbers to open the lock.
The #is: 468ODBLK.

Thank you to anyone who can tell me the easiest way to open this lock.

12. Mary says:

I have a Master Luggage lock with three rows of numbers. It is locked and I cannot open it since I do not remember the combination. The Lock Number is: 468ODBLK.

Thank you for your help! 8-)

13. neoanarchist says:

Hey, does anyone know the exact mathematical equations that are behind the generated 100 combinations? I’d like to program this on my calculator in Q-Basic and was wondering if anyone could help me out.

If you can, please email me the necessary math to injection@gmail.com

14. Alexej says:

I have a Master lock (40 numbers dial), 3 numbers combination to open
I remmember only that first # is 0
lock # 909567
pls help if you can

15. Spazz says:

can sum1 explain the difference between the newer and older dial master lock latch bars…i just pent 15 min. trying to shim what i think is a newer model, cuz iv done it before fine

16. Kevin says:

i have a 40 number master lock that i have no clue what the combo is, is there any way to find out the combo except guessing if you know email me at dewfreak81@yahoo.com

17. marty says:

well i got a 40 number masterlock, i seen the video but i don’t understand it. can somebody please email me back to tell me how to crack it?? thx

18. andrew says:

hey i need the combo for a backpack lock model

19. Ken Manley says:

Like Doug, I have misplaced the combo to my Master Lock 4 digit combo, #175. Any help would be appreciated.

20. Ovidsmuse says:

Just so everyone knows, I bought two brand new masterlocks today, name brand with the black dial. Shim does not work, and I’m not suprised. Finding the 12 digit’s and eliminating 11 of them, then using modulo 4 to further get 100 combinations still works. I opened the new lock without looking at the combiniation in under 5 min. Then I opened another older lock my roomate had forgoton the combo for in about 8. (the combination was further down the list of possibilities that the first one.)
One thing to remember is that most locks are made to be exploited, so a locksmith can unlock them if need be.

21. Ovidsmuse says:

Just so everyone knows, I bought two brand new masterlocks today, name brand with the black dial. Shim does not work, and I’m not suprised. Finding the 12 digit’s and eliminating 11 of them, then using modulo 4 to further get 100 combinations still works. I opened the new lock without looking at the combiniation in under 5 min. Then I opened another older lock my roomate had forgoton the combo for in about 8. (the combination was further down the list of possibilities that the first one.)
One thing to remember is that most locks are made to be exploited, so a locksmith can unlock them if need be.

22. Toni says:

I somehow set my 3 digit master lock incorrectly, so i too need to know a way to crack it. Marty, where can i get this video u are talking about?

23. Philip J Fry says:

You can make a verry crude version of the lock shim by using the dust sleeve of a floppy disk and cutting it down to look like the one in the video, i did this and have a working shim for my Combo lock.

24. wim says:

richard feynman’s autobiography where he talks about doing this at los alamos in the 1940s is fun.

25. Chovy says:

I may have found a flaw in this entire hack. I just purchased a master lock, yes a true MASTER LOCK. The combination was 23-28-33.
If I’m not mistaken, and I have taken CALC 1250.
23 and 33 are not modualarly equivalent.

Does anyone have any clue whats going on.

26. Anonymous says:

More important:
Does anyone have any clue what ‘modualarly equivalent’ means?

:-p

27. jr says:

That is odd. My best explanation is that the locks are not accurate down to the number. The algorithm would yield 21 and 25 (both of which are congruent to 33 mod 4), and it’s possible that 22 falls within the effective range – the room for error – of one of those values. Another consideration is that the given final value might not be quite right either – try to find the last value using the procedure as given, you might find it isn’t exactly 33. If it’s 35, for instance, that’s congruent to 23 mod 4. If it’s 34, then it’s congruent to 22 mod 4, and 22 could easily be in the same range as 23.

Anyhoo, that’s my best guess.

28. Fräulein says:

I tried the method posted by strazzere, using shims made from the metal on a diskette. EXCELLENT! I got the lock open immediately.
I used to do it the old fashioned way, by dialing the numbers, listening and pulling the hasp – that was never 100 percent accurate and took effort and time. This method so far has been 100 percent and never takes long.

PS – I used this for “good”. Students do things that they think are funny, like locking their combination lock onto other peoples property, which requires the bolt cutters to be found. This year THEY were the ones who would have to go look for a set of bolt cutters, to remove someone elses lock from the handle on their back pack.

Thank you for the new and improved version to pop a lock. :D Many kisses.

29. marty says:

toni go all the way up the page and its a little text ill copy past it for ya : UPDATE: x04d sent in a video demo (DivX) of how to open a lock in 2 sec. using a padlock shim.

its under the small text on top

30. marty says:

i made a padlock shim but i dont know where to put it in so i tried the shacle and it dosent fit in so could anyone help me cause all my stuff is in it :S

31. lwc says:

23-28-33? Seems it is about mod 10, or mod 5.

32. brian says:

Just bought two master locks today. One standard black, model 1500D combo 39-25-31. This one cracked by the book.

The other green, model 1529D combo 15-20-33 was difficult to find the last digit. I finally peeked and found the same problem that Chovy found. 33 mod 4 is 1 (33/4=8 rm 1), so the first digit combos should be: 1, 5, 9, 13, 17, 21, 25, 29, 33, 37. The actual first digit is not on the list. I tried using 13 and 17 with no luck. Maybe this trick only works with certain models?

33. brian says:

Many apologies… I just doubled checked and 13-19-33 does in fact work.

34. user says:

As far as security is concerned, it’s not that hard to break open a combination lock, from what I remember. All you have to do is put a metal bar, preferably one that’s about the same thickness of the space of the shackle, inside the shackle and pull/push down. It breaks off quite easily.

35. sue says:

I’ve found a way to open master #175 combo locks in less than 2 seconds using a very easy to make tool.
Also works on sesame combos…these type of padlocks look secure but are actually the easyest locks to open.
email me for info. zoome_1@yahoo.com

36. zoome says:

This is the last time i will post this here …so listen up….I can show you how to make a key to open all #175 master combo locks, (thats the brass thumbwheel type, NOT THE CHEAPER DIAL TYPE,that is used mostly in locker rooms.)Its really amazing how easy it is…This is NOT A SHIM TOOL..it is a very easy to make KEY that will open ALL #175 master combination locks faster than you can work the combination!!!this is your last chance to be the first to learn this trick…I’ve looked all over the internet and have seen nothing on this hack…E-MAIL ME FOR DETAILS NOW….zoome_1@yahoo.com

37. Betty says:

I have two Master combination locks that have unknown combinations. Can you help to break the lost codes for me to use the locks? Appreciate your input.

38. Elena says:

People, please send me the letter, how to open master locks or locks like Dudley, cause i forgot how to open my lock and i really need it to open it right now!! please hurry and send it plz~~!!

39. BofH says:

Ok well. Our company backup files get taken offsite in a canister with a platic and wire seal and a crappy little padlock that needs a crappy little key. I once manage to break the seal and use the wire to crack the lock in about 5 minutes. I lost the key. Doin it ever since.

40. LOCKER1 says:

One way to test a bolt cutter before buying it would be, if you’re in a hardware store, they have a bolt cutter they use themselves to cut chain–some times it is a fixed machine type thing but sometimes it is just a boltcutter. So ask them to look at their boltcutter and see if the jaws in particular are the same quality as the ones they sell. Ask if they cut case hardened chain with their cutter. And also just tell them you are buying this cutter for such and such a purpose and get them to assure you it will do the job. Then if it doesn’t, you’ve got a good reason to bring it back (with the thing it won’t cut would be good) and get a refund. If they get tough the legal angle is they warranted it (represented it) (orally) to be useful for a particular purpose, you relied on their representation, and their warranty was breached.

41. Don AR says:

Hey.. I work for a big machining company, and this one job we were doing, a company gave us a huge steel locker with a 0-99 combination on it. Is there any chance i can break this, or should i just get it drilled. Its been locked for about 2 years now and really just want to get inside lol.

42. Kevin says:

I have combo padlock with a hole on the back and how do i make a key and get the key cut to the open the padlock the lock is model #1525 and wana find out how i can make a key that will open it. Can anyone that know,s how please email me at kevin.msmith@yahoo.com

43. rofl says:

we used to use this and shims to play pranks on ppl at school. but my school forces us to use master locks with a key hole in the back for a master key. so we made our own key from tearing it apart and looking at the pin heights. took a while to get it right but it works on every school lock.