How do I measure for a zipper?

Measure the opening where the zipper will be inserted, from the top stop position to the bottom. The zipper should be at least 2–3cm longer than the opening. For invisible zippers, measure to the waistband seam.

What are standard UK zipper lengths?

UK zippers come in standard lengths: skirt/trouser zips 15–23cm, dress zips 51–61cm, jacket zips vary. You can shorten a longer zipper by sewing a new bottom stop, but you cannot lengthen one.

What type of zipper should I use?

Invisible/concealed zips: dresses, skirts (invisible from outside). Metal zips: jeans, jackets (decorative, strong). Nylon coil: general purpose, lightweight. Open-ended: jackets and coats (separates fully).

SewCalcs

Zipper Length Calculator — Correct Zip Size

Determine the correct zipper length for garments and projects.

Opening Length

Length of the zipper opening

Garment Type

How We Calculate This

The zipper length is the opening measurement plus 2.5cm for the stops and ease.

The formula

Minimum zipper = Opening length + 2.5cm

Round up to the next standard size available.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.