Also known as zipper size, the gauge of a zipper refers to the width of its teeth, in millimeters, when it’s zipped shut. Whenever you see a number and hash symbol (e.g., #2) next to a zipper, this is referring to the zipper’s gauge.

The larger the number, the heavier the gauge, and, therefore, the heavier the zipper.

Measuring zipper gauge is easy. Measure the zipper teeth, in mm, horizontally when the zipper is closed. Make sure you don’t include any tape in your measurement – it’s just the teeth you want to measure.

You can use a measuring tape, ruler, or digital caliper. If your measuring tool only includes cm and inches, convert them to mm to figure out the gauge (1cm = 10 mm; 0.25” = 6.35mm).

Some guides suggest looking at the back of the zipper's slider to determine the zipper gauge, but this isn’t the best solution. The letters and numbers on the back can mean a whole host of things, depending on the manufacturer.

The best - and most reliable - way to determine a zipper's gauge is to measure the zipper yourself.

If you’re working with a broken zipper that no longer
closes, you can work out its gauge by measuring one side and doubling it. You might have to round up or down slightly (to account for any overlap that occurs when the teeth are closed), but it should be fairly clear what the gauge is based on the measurement of a single side.

Generally, measuring the length of a zipper is easier than measuring the gauge of a zipper.

Zipper length is often measured in inches. The guidelines for measuring a zipper's length differ slightly based on type of zipper.

Regardless, you never include any zipper tape where there’s no chain in your measurement. To put it another way, zippers will always have some extra tape at the top and sometimes on the bottom, which is usually for cutting and sewing depending on the project. You don’t include this in your length measurement, as it’s essentially “waste” material in this regard.

Closed-end zippers are pretty easy to measure because they have obvious ends.

Measure the length from the top of the top stop to the bottom of the bottom stop to get the required length.

Also known as open-end zippers, these are just as simple to measure.

Go from the top of the top stop to the bottom of the retainer box, which is the part that keeps the zipper on its chain.

Two-way separating zippers don’t have retainer boxes at the
bottom, as the second slider covers this purpose.

As such, you’ll want to measure from the top of the top stop to the bottom of the reinforcement tape.

Two-way bag-style zippers are closed-ended, and similar to one-way closed-end zippers, they are measured from end to end from each stop.

Unlike one-way closed-end zippers, however, these zippers have a bottom stop at each end, as opposed to a bottom stop at one end and top stops at another.

Measure from the top of one bottom stop to the bottom of the other bottom stop.

Now that you know how to properly measure zipper gauge/size and zipper length, you can shop for what you need.

Our helpful shop filters will allow you to segment your searches by gauge and length.

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