How Do You Measure Zipper Length To Replace It?

Measure the teeth from the top stop to the bottom stop, leaving out spare tape. Separating and two-way zippers have their own rules.

Published October 30, 2026 · 3 min read · Topic: Repairs, Zippers & Hardware · Repairs & hardware

Typical situation

A zipper on your duffel bag has failed and you are ordering a replacement, but you are not sure how long it should be.

Main answer · berabags Editorial Team · Repair view

Measure from the top of the top stop to the bottom of the bottom stop, and leave out any spare tape. Zipper Shipper says that you never include zipper tape where there is no chain, and that different types of zipper are measured slightly differently.

What the guide says

Closed-end zippers are measured from the top of the top stop to the bottom of the bottom stop.
One-way separating zippers are measured from the top of the top stop to the bottom of the retainer box.
Two-way separating zippers have no retainer box, so they are measured from the top of the top stop to the bottom of the reinforcement tape.
Head-to-head, two-way bag-style closed-end zippers have a bottom stop at each end, and are measured from the top of one bottom stop to the bottom of the other.
Zippers always have some extra tape at the top, and sometimes the bottom, which you do not include.

How to measure your bag zipper

Lay the bag flat and close the zipper.
Identify the type: closed-end, separating or two-way bag-style.
Measure the correct points with a rigid ruler or tape.
Write it down in inches or centimetres.
Photograph the zipper next to the ruler.

A common mistake

Measuring the tape instead of the chain makes the zipper too long. A supplier who sells zippers by the inch will usually ask for the chain length.

Where this answer stops

This is general guidance from a zipper seller. A bag with curved zippers or a unique shape may need a custom length, and a repair shop can help with that.

Sources and further reading

Zipper Shipper: How to measure a zipper, size/gauge and length

Three more perspectives

berabags Editorial Team · Maintenance view

Measure the old zipper before you cut it out. Once it is removed, you lose the reference, and an error of an inch can mean a gap or a pucker.

berabags Editorial Team · Selection view

Check which kind of zipper you have: closed at the bottom, separating, or a two-way bag zipper with a slider at each end. The rule changes with the kind.

berabags Editorial Team · Use view

Do not include the spare tape at the ends. The extra fabric on the tape is for sewing, and it is not part of the length that you need to order.

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