Quick answer: Most gym, school, and employee lockers in the US, UK, and EU use a hasp with a 5/16" (8mm) hole and a 7/16" (~11mm) clearance for the latch. The best-fitting padlock is a 1-9/16" (40mm) body with a 1-3/4" (44mm) shackle — exactly the SEPOX 40mm laminated-steel and brass series. A 1-1/2" (38mm) body also fits. A 1-3/4" (44mm) body usually does not fit the hasp slot. For swimming-pool and outdoor lockers, choose a weatherproof or covered model (the S-Padlock and NA123 series at SEPOX) to prevent rust. SEPOX 40mm gym-locker sets start at $11.99 (1-pack), $12.98 (2-pack keyed-alike), and $19.99 (4-pack).
Why locker size matters more than lock quality
A great padlock is useless if the hasp does not fit. Most returned "wrong size" gym padlocks are 50mm+ bodies that physically cannot pass through the locker hasp slot. The right size is smaller, not bigger.
Standard locker hasp dimensions
| Locker type | Hasp hole diameter | Vertical clearance | Best padlock body |
|---|---|---|---|
| US gym/school (standard) | 5/16" (8mm) | 7/16" (~11mm) | 1-9/16" (40mm) body, 1-3/4" shackle |
| US full-height gym | 3/8" (10mm) | 1/2" (13mm) | 1-3/4" (44mm) body, 2" shackle |
| UK/EU employee lockers | 8mm | 11mm | 40mm body fits |
| Swimming pool / outdoor | 8–10mm | 11–13mm | 40mm weatherproof body |
If you don't have a ruler, the simple rule: the padlock body width should be no more than 1-9/16" (40mm) for most gym lockers.
Choosing the right shackle length
Once the body fits, the next decision is shackle length:
- Standard (7/8" / 22mm): fits flush-mounted hasps, common on smaller lockers.
- Long (1-3/4" / 44mm): needed when the hasp sits proud of the door, common on full-height gym lockers.
- Extra-long (2-3/8" / 60mm): for hasps with extra clearance (gate + locker combos, locker rooms with recessed handles).
For a typical gym locker, 1-3/4" long shackle is the safe default.
SEPOX models that fit gym lockers
| Model | Body | Shackle | Price (1-pack) | Best for |
|---|---|---|---|---|
| 40mm solid brass chamfered | 40mm | 1-3/4" | $19.99 | Indoor gym, premium look |
| 40mm steel 1-9/16" KA | 40mm | 1-3/4" | $14.97 | Daily gym, durable |
| 40mm 2-3/8" extra-long KA | 40mm | 2-3/8" | $14.97 | Recessed-handle lockers |
| 40mm brass stainless SUS304 | 40mm | 1-3/4" | $12.99 | Locker room with moisture |
| Trinity aluminum RGB 4PK | 1-1/2" | Long | $34.99 | Color-coded family lockers |
What NOT to buy for gym lockers
- Anything 50mm+ body. Will not fit the hasp. (SEPOX 80mm and 70mm models are for sheds, gates, warehouses — not lockers.)
- Smart locks / Bluetooth padlocks. Battery dies → locker is permanently locked. Gym staff will not help.
- Cheap luggage-style combination locks. Most gym thieves can shim or cut these in under 10 seconds.
Why gyms often recommend combination locks
Many gyms prohibit key locks because lost keys mean cut locks. A resettable 4-digit combination is the safe middle ground:
- User changes code if they forget it (no locksmith visit).
- Gym master code can be set aside (the gym doesn't need it).
- No key to lose.
If your gym allows combination, see our resettable combination guide.
Care tips for locker-room padlocks
- Wipe dry after each use if your gym has a pool — even "weatherproof" models last longer when toweled off.
- Lubricate the shackle every 3 months with a graphite or silicone spray (not WD-40 long-term — it attracts dust).
- Don't store the lock attached to the locker — home it in your bag. Permanent attachment lets thieves cut the hasp instead of the lock.
FAQ: gym locker padlocks
Will a 50mm padlock fit a gym locker? Usually no. Most gym locker hasps have only 7/16" (11mm) of vertical clearance, and a 50mm body is too wide to pass through the slot. Use a 40mm (1-9/16") body instead.
Do gyms allow keyed padlocks? Many do, but an increasing number of gyms prohibit them because a lost key means the gym must cut the lock. A resettable combination padlock avoids this problem and is accepted almost everywhere.
Can I leave my padlock on the locker between visits? Most gyms require you to remove it. Leaving a lock permanently attached lets a thief cut the hasp instead of the lock — and the gym will charge you for the damaged locker. Take it home in your bag.
What if my locker has a built-in combination lock? Then you don't need a padlock at all. Check the inside of the door: if you see a dial or keypad, the locker is self-locking and a padlock will not fit.
Is a combination padlock as secure as a keyed one? For gym lockers, the threat model is opportunistic theft, not a determined attacker. A 4-digit resettable combination lock with a hardened steel shackle is sufficient. The weakest point in most gym locker rooms is the locker door itself, not the lock.