How wide is a #5 zipper in millimeters?

Q: How wide is a #5 zipper in millimeters?

A #5 zipper measures about 6.0 to 6.3 mm across the meshed chain, measured over the closed teeth at the widest point. That figure is the chain width and is the number buyers usually compare between suppliers.

The finished assembly is wider because the tape is part of it. A single #5 tape is typically 12.5 to 14 mm wide, so the complete zipper laid flat measures roughly 30 to 33 mm from tape edge to tape edge. Closed thickness, including both tapes and the meshed teeth, usually falls between 2.0 and 2.5 mm.

For pattern making, what matters more than total width is the distance from the tape edge to the center of the teeth, often called the seam allowance position. On a #5 this is commonly 6 to 7 mm. Confirm it on the actual sample, because tape construction and coating thickness shift these numbers by a few tenths of a millimeter, which is enough to affect a tight seam.