Why Padlocks Have a Hole in the Bottom

Animated Short, 0:40. Published 2026-11-11.

What is the small hole in the bottom of a padlock for?

Padlock hole in bottom? It's a drain, so rain that gets in runs out and can't freeze the lock shut.

The story is made up; the science is real: lock makers put a small drain hole in the bottom of padlocks so water that gets inside runs out. Trapped water can freeze in the cold and jam the lock, and it rusts the parts inside. The same hole takes a drop of lock lube when a lock gets stiff.

Sources: ASSA ABLOY padlock spec ("drainage holes in the padlock body prevent freezing"); Monroe Engineering; House Digest.

Transcript

He drilled a hole in the bottom of every padlock. Two locksmiths, one deal, every gate in town. The mayor sees the holes and turns red. You're selling me broken locks! But he won't plug one. The other guy seals his tight, and wins. He only gets the old fire barn. The town calls his Swiss Cheese Locks.

Then the rain comes. By November, the sealed locks slosh. Because rain always gets in. And a sealed lock has no way out. That first freezing night, his locks drip dry. The sealed ones freeze solid. Then the fire alarm rings. Every gate in town is frozen shut. Except the fire barn.

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