Zipper Length Guide
The right zipper length depends entirely on what it's going into.
| Project | Typical zipper length | Common type |
|---|---|---|
| Dress/skirt back or side | 7–9 in | Invisible |
| Pants/jeans fly | 5–7 in | Regular or separating (fly) |
| Cardigan, vest | Garment front length | Separating |
| Jacket, coat | Garment front length | Heavy-duty separating |
| Throw pillow cover | Pillow width minus 2 in | Regular |
| Zippered pouch/bag | Bag opening width | Regular or continuous chain |
| Sleeping bag | Full length of the bag | Heavy-duty separating |
Measure the opening, not a guess
For anything with a fixed seam length (dress zipper, pillow cover), measure the actual seam the zipper will sit in and match it as closely as the available lengths allow, rather than assuming a "standard" size — dress zippers alone commonly range from 4" to 22" depending on the garment.
Front-opening garments need the exact front length
Jackets, cardigans, and vests need a separating zipper measured to the garment's front opening length, from the top of the neckline to the bottom hem — this is one measurement you genuinely have to take from your own pattern rather than look up on a chart.
Buying slightly longer is usually fine, shorter usually isn't
A too-long zipper can be shortened (bar-tack and trim the excess, or just let the pull stop short of the top), but a too-short zipper can't be lengthened. When in doubt between two available lengths, size up.