You shorten a regular or an invisible zip from the bottom: measure the length you need down from the top stop, sew a new stop across the teeth at that point, by hand with strong thread or with a wide zigzag, and cut the tape off 2 cm (3/4 in) below. A separating zip is shortened from the top instead, because its box and pin at the bottom must stay: pull the teeth off above the new length with pliers, then fit new top stops or fold the tape ends into the facing. A metal zip follows the same logic with the teeth removed by pliers before a new stop goes on.
Why shorten a zip instead of buying the right length?
Shops stock standard lengths, roughly 10, 12, 15, 18, 20, 22, 25, 30, 40, 50 and 60 cm (4 to 24 in), in a limited range of colors. A longer zip in the right color is often the only one on the shelf, and a zip is cut to size in a few minutes. Buying longer also gives you room for error when you insert it, especially with an invisible zip, where the last couple of centimeters above the pull cannot be sewn.
What you need to shorten a zip
- The zip, at least 2 to 3 cm (3/4 to 1 1/4 in) longer than the opening
- A tape measure and tailor's chalk or a marking pen
- A hand needle and strong thread (topstitching or buttonhole thread), or a sewing machine with a zigzag stitch and a zipper foot
- Old scissors for cutting tape and coil; keep your fabric shears away from the teeth
- Flat-nose pliers and end-cutting nippers for metal and moulded plastic teeth
- Replacement metal stops, sold in packs by notions suppliers, for metal and separating zips
How long should the zip be?
A zip's length is measured from the top stop to the bottom stop, not from end to end of the tape. The pattern's notions list gives the length for the opening it was designed for; the invisible zip glossary entry explains why an invisible zip is usually listed 2 to 3 cm longer than the opening. If you are adding a zip where the pattern had none, measure the opening on the seam line, from the top of the finished edge (below the waistband or facing seam) to the point where the seam closes, and buy that length or longer.
| Zip type | Shorten from | New stop | Watch out for |
|---|---|---|---|
| Regular coil (nylon) | Bottom | Zigzag or hand bar tack | Pull off the end before the stop is made |
| Moulded plastic | Bottom | Hand bar tack | Needle breaks on the teeth |
| Invisible | Bottom, after inserting | Zigzag over the coil | Room for the pull above the seam end |
| Metal | Bottom | Metal stop or bar tack after removing teeth | Never machine-stitch across teeth |
| Separating (open-end) | Top | Metal top stops or folded tape | Keep the box and pin at the bottom |
How do you shorten a regular coil or plastic zip?
- Close the zip and measure from the top stop down the length you need. Mark across the teeth with chalk.
- Make a new bottom stop at the mark. By hand: thread a needle with doubled strong thread, bring it up through one tape beside the teeth, and wrap 8 to 10 tight stitches over the teeth and through both tapes, finishing with a knot on the back. By machine, on nylon coil only: set the zigzag to its widest, 5 to 7 mm, and the stitch length to 0, lower the needle beside the coil with the handwheel, and sew 8 to 10 stitches across it. Moulded plastic teeth deflect the needle; use the hand method.
- Cut the tape 1.5 to 2 cm (5/8 to 3/4 in) below the new stop. The stub is caught in the seam or the facing later, so leave enough to sew through. Round the two corners to reduce bulk.
- Test the slider. Run it down to the new stop and back; it should stop cleanly without catching.
The top of a regular zip is left as it is; its stops are hidden in the waistband or facing seam. The lapped zip and the exposed zip posts show where the stub goes in each insertion.
How do you shorten an invisible zip?
An invisible zip is shortened after it is sewn in, not before. Its coil rolls inward, the pull has to be pushed below the stitching while you sew, and the extra tail gives you room to do that.
- Insert the zip with the full length hanging below the opening, following the invisible zip guide.
- Close the seam below the zip, sewing past the end of the zip stitching by 1 cm (3/8 in).
- Pull the slider up, then make a stop 1 to 2 cm (3/8 to 3/4 in) below the end of the seam: a wide zigzag over the coil with the stitch length at 0, or a hand bar tack through the coil and both tapes.
- Cut the tape 2 cm (3/4 in) below the stop and tack the stub to the seam allowance so it does not flap.
How do you shorten a separating zip?
A separating zip opens from the bottom, where a box on one tape receives a pin on the other. Those parts cannot be remade at home, so the zip is shortened from the top.
- Measure from the bottom stop upward the length you need, usually the opening of the jacket from the hem to the neck seam. Mark across both tapes.
- Open the zip and move the slider to the bottom, out of the way.
- Remove the teeth above the mark. On moulded plastic and metal zips, grip each tooth with flat-nose pliers, twist a quarter turn and pull it off the tape; clear about 2.5 cm (1 in) above the mark. On a coil zip, cut the coil off above the mark with old scissors and pull out the few remaining stitches that held it.
- Fit new top stops, one on each tape, squeezed on with pliers over the last tooth. Without stops, fold each empty tape end to the back at a 45° angle and stitch it down; the folded tape blocks the slider and disappears inside the neck seam or hood seam.
- Cut the tape 1.5 cm (5/8 in) above the last tooth, or at the garment's seam allowance if that is longer.
Check that the slider rides up to the top and stops before you sew the zip in.
How do you shorten a metal zip?
A closed-end metal zip is shortened from the bottom like a coil zip, but the teeth must come off before the stop goes on, because a needle cannot pass through them. Mark the length from the top stop, pull the teeth off below the mark with pliers or nippers over about 2.5 cm (1 in), then fit a new metal bottom stop over the last pair of teeth or sew a bar tack through the bare tape with strong thread. Cut the tape 2 cm (3/4 in) below.
What are the common mistakes when shortening a zip?
- Measuring the tape instead of stop to stop. The zip ends up 3 to 4 cm (1 1/4 to 1 5/8 in) short.
- Cutting before making the stop. The slider runs off the end. A coil slider can be threaded back by feeding both tapes in evenly; an invisible zip slider usually cannot.
- Machine-sewing across metal or moulded teeth. The needle breaks and can mark the plate.
- Shortening a separating zip from the bottom. The box and pin go with it.
- A stub shorter than 1.5 cm. Nothing to catch in the seam, and the stop sits at the raw edge.
- No room for the pull on an invisible zip. The last 2 cm above the stop cannot be sewn, so the opening gapes at the bottom.
When should you buy the exact length instead?
Buy to length for an exposed zip whose stops will show, for a metal jeans fly, where the lengths on sale already match most patterns, and for a separating zip when the right length exists in the right color: removing twenty teeth with pliers is slow work. Otherwise a longer zip is the safer buy. Invisible zip vs regular zip helps you pick the type, and if you draft the garment with Sewly, the notions list in the sewing guide gives the zip length for the options you chose, so you know what to buy before you leave the shop.