How does a zipper work?
Short answer
A zipper works by moving a slider along two fabric tapes lined with metal or plastic teeth. The slider's internal Y-shaped channel angles and forces the opposing teeth to interlock when pulled in one direction, and separates them when moved in the opposite direction.
about a 20-second read
The mechanism behind the closure
Each tooth on a zipper features a projection on top and a matching cavity underneath. As the slider moves forward, its Y-shaped internal channel guides teeth from both sides toward each other at an angle. This angle allows each tooth to slip cleanly between teeth on the opposing side. As the teeth straighten out at the narrow end of the channel, they lock together securely. Moving the slider in reverse acts as a wedge, forcing the teeth apart at an angle so they disengage.
Parts of a zipper
Slider
The moving component that travels along the chain. It contains the Y-shaped channel that forces the teeth together or apart.
Pull tab
The tab attached to the slider that you hold to pull the mechanism up or down.
Teeth
The individual elements made of metal, molded plastic, or continuous coil that interlock to close the opening.
Tape
The fabric strips on either side to which the teeth are attached and which are sewn into garments or bags.
Top and bottom stops
Fixed stops at the ends of the tape that prevent the slider from sliding off the chain.
Built-in locking mechanism
Many sliders feature an integrated locking mechanism to prevent the zipper from opening on its own. A small spring-loaded pin sits beneath the pull tab. When the tab is released, the pin drops between the teeth, locking the slider in place. Pulling the tab lifts the pin away from the teeth, allowing the slider to move freely.
Repairing damaged teeth
It is a common misconception that individual broken or missing zipper teeth can be replaced. Because teeth are crimped, molded, or woven directly onto the tape, single teeth cannot be reattached. If a tooth is missing, the chain will jam and the entire zipper must be replaced. Sliders and stops, however, can often be replaced separately.
Brief summary
A zipper functions by using a slider with a Y-shaped channel to angle two rows of opposing teeth together until their projections interlock. Moving the slider in reverse wedges the teeth apart. The closure remains secure due to the shape of the teeth and often a spring-loaded lock inside the slider.
Sources
- Zipper - Wikipedia — Wikipedia (Accessed 2026-09-12)
- Blixtlås - Wikipedia — Wikipedia (Accessed 2026-09-12)
- Anatomy of a Zipper - Sailrite — Sailrite (Accessed 2026-09-12)
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