How to Measure for a Zipper

How to Measure for a Zipper
One of the most common questions we field from designers and makers here in the New York Fashion District is simply, "What size zipper do I actually need?"

Measuring incorrectly is the number one reason for mismatched hardware and frustrating returns. The confusion usually stems from one simple mistake: measuring the entire length of the fabric tape.

Here is the definitive, industry-standard method for measuring zippers so you get a perfect fit every single time.

1. The Golden Rule of Zipper Measurement

When you buy a zipper labeled "18 inches," that measurement does not refer to the total length of the product end-to-end.

  • The Rule: Only measure the functional part of the zipper.

  • Why: You must measure from the top stop down to the bottom stop. The extra fabric tape extending past the stops is meant for sewing into your seam allowance and is never included in the official length measurement.

2. How to Measure a Closed-End Zipper

Closed-end zippers are used for pants, skirts, bags, and pockets—anywhere the two halves of the zipper don't need to completely detach.

  • Step 1: Zip the zipper entirely closed and lay it flat on a table without stretching the fabric tape.

  • Step 2: Place the "0" mark of your measuring tape exactly at the top edge of the top stop. Measure straight down to the bottom edge of the bottom stop.

3. How to Measure a Separating (Open-End) Zipper

Separating zippers are used for jackets, hoodies, and coats where the two sides completely detach at the hem.

  • Step 1: Zip the zipper entirely closed and lay it perfectly flat.

  • Step 2: Place the "0" mark at the top edge of the top stop, and measure straight down to the very bottom of the retainer box (the chunky piece at the bottom where the pin is inserted). Ignore the fabric tape extending below it.

4. What If You Are Between Sizes?

Authentic YKK zippers are manufactured in standard lengths (usually 1-inch or 2-inch increments).

  • The Solution: Always size up.

  • Why: It is easy to shorten a zipper, but impossible to lengthen one. If you need a 17-inch zipper, purchase an 18-inch version. You can simply pull a few teeth from the top and fold the tape over to achieve the exact millimeter length your garment requires.

Ready to Measure Twice and Order Once?

By ignoring the extra fabric tape and focusing only on the "stops," you will perfectly match your hardware to your pattern requirements.