How to choose zipper length is one of the most common questions in sewing and clothing repairs. A zip that is too short makes a garment hard to put on, while one that is too long sticks out or needs shortening. The good news is that there are clear measuring rules and typical lengths for every kind of item. Here you'll learn how to measure a zipper, how much to add to the opening and which lengths are used most often.
How to measure zipper length
Zipper length is measured from the top of the top stop to the bottom of the bottom stop (or the box on a separating zip). The tape above and below the teeth is not included. If you are replacing an old zipper, close it and measure exactly this way – that is the length you need.
If you're sewing a new garment, measure the opening along the seam line, from the top edge (minus the seam allowance) to where you want the zip to end.
Light green #3 spiral zippers TAT TF875 – 16 to 56 cm non-separating
Metal zipper non-separable blue / gold teeth T5 PMZ1006
Metal closed-end zipper yellow / silver teeth T5 PMZ0003How much to add to the opening
- Regular closed-end zipper: the same as the opening or up to 1 cm longer.
- Invisible zipper: 2–3 cm longer than the opening, because the bottom section can't be stitched closely.
- Separating jacket zipper: exactly the length of the front from hem to collar edge, minus allowances – there is no leeway, as it can't be shortened from the bottom.
- Bag or cushion zipper: 3–5 cm shorter than the side, to leave room for the corners.
If you're torn between two sizes of a closed-end zip, take the longer one – it is easy to shorten. For separating zips, look for the exact size.
Typical zipper length chart
| Item | Typical length | Recommended type |
|---|---|---|
| Children's trousers | 10–12 cm | No.3 coil, closed-end |
| Women's trousers | 14–18 cm | No.3 coil, closed-end |
| Men's trousers | 18–20 cm | No.3–No.5 coil or metal |
| Jeans | 15–20 cm | No.5 metal, closed-end |
| Skirt | 18–22 cm | No.3 invisible or coil |
| Dress (side zip) | 30–40 cm | No.3 invisible |
| Dress (back zip) | 40–60 cm | No.3 invisible |
| Hoodie, light jacket | 50–65 cm | No.5 separating |
| Winter coat | 60–80 cm | No.5–No.8 separating |
| Cushion cover 40 x 40 cm | 35 cm | No.3 coil |
| Cushion cover 50 x 50 cm | 45 cm | No.3–No.5 coil |
| Pouch, small bag | 18–25 cm | No.3–No.5 coil or metal |
These figures are a guide – always measure the specific pattern and size.
Closed-end or separating – does it affect length?
Yes. A closed-end zipper can be shortened from the top or the bottom, so it forgives small mistakes. A separating zip has a fixed bottom end and can only be shortened from the top – on metal or moulded plastic zips this means removing teeth with pliers. That's why it pays to measure jackets carefully and order the exact length.
What we offer
At Bul-tex you'll find closed-end No.3 coil zippers in lengths from 10 cm to over 50 cm and dozens of colours, a coil zipper range in 14, 16, 18 and 20 cm, and No.5 metal zippers in 20, 30, 40 and 50 cm – ideal for jeans, bags and decorative details.
Frequently asked questions
Is the tape included in the zipper length?
No. Length is measured along the teeth only, from the top stop to the bottom stop. The tape above and below is extra.
Which zipper should I buy if I need 17 cm?
Get an 18 or 20 cm closed-end zipper and shorten it from the bottom to 17 cm – it takes a few minutes.
What zipper length do I need for a 40 x 40 cm cushion cover?
Around 35 cm. That leaves 2–3 cm at each end for neat corners while the cover is still easy to remove.
Browse all zippers by length and colour, or see our metal zippers for jeans and bags.
