How to Replace a Broken Zip in a Dress Without a Tailor

A favourite dress with a broken zip usually ends up at the back of the wardrobe, waiting for a tailor visit that never happens. Months later it goes to a charity bag or the bin, even though the fabric is perfect and the fit is still right. Learning to replace a broken zip yourself takes one afternoon, costs about 3 pounds in parts, and keeps a dress you love in use for years.

Before you unpick anything, though, find out what has actually failed. Many "broken" zips need five minutes of work, not a full replacement.

Diagnose the zip before you replace it

Zip problems fall into three groups, and only one needs a new zip:

• The slider splits the teeth open behind it. The teeth are fine; the slider has worn and loosened. This is the most common fault on dresses and can be fixed without removing the zip.
• The pull tab has snapped off. Replace the tab with a split ring or a clip on puller from a haberdashery for about 1 pound.
• Teeth are missing, bent or the tape is torn. This needs a new zip.

Run the slider up and down slowly in good light. If the teeth zip together and then split as you move away, it is the slider. If the slider jams in one place or skips, look closely at that spot for a missing or twisted tooth.

The five minute fix most broken zips need

Most sewing guides jump straight to unpicking and fitting a new zip. I disagree with that order. In my experience mending dresses for friends and readers, well over half of zips described as broken just have a slider that has opened up from years of use. Replacing the whole zip then means a two hour job and the risk of puckering a good seam, when the zip tape itself had decades left in it.

To tighten a worn slider on a metal or moulded plastic zip, close the zip, then use small pliers to squeeze the back end of the slider very gently, a fraction of a millimetre on each side. Test, then squeeze again if needed. Too much pressure cracks the slider, so work slowly.

On a coil zip, which is the type in most invisible dress zips, a loose slider is better replaced. Buy a matching slider in the same size, usually marked as number 3 or 5 on the back of the old one. Ease the old slider off the bottom of the zip after removing the bottom stop with pliers, thread on the new one, and crimp a new stop in place. Replacement slider kits cost 2 to 4 pounds.

What you need to replace a broken zip

If the teeth or tape have failed, gather these before you start:

• A new zip of the same type and length. Measure the old one from the top stop to the bottom stop. Most dresses use a 22 cm or 56 cm invisible zip; side zips are often 18 to 20 cm.
• A seam ripper, sharp scissors and pins or clips
• Matching polyester thread
• A sewing machine with a zipper foot, or an invisible zipper foot for concealed zips. Hand sewing works too but takes two to three times longer.
• An iron and a pressing cloth

Match the zip type. Invisible zips have the coil on the back and disappear into the seam. Regular zips show the teeth. Swapping one for the other changes how the dress looks, so stick with the original unless it was the wrong choice all along.

How to replace a broken zip step by step

1. Photograph the inside. Take photos of how the lining, facing and waist seam meet the zip. You will need them later.
2. Unpick carefully. Use the seam ripper to remove the stitches holding the old zip, plus 3 to 4 cm of the lining or facing around it. Cut threads every few stitches rather than pulling the ripper along the seam, which can tear thin fabric.
3. Press the seam allowances flat at a temperature that suits the fabric. Pressing now makes the new zip go in straight.
4. Pin or clip the new zip exactly where the old one sat. For an invisible zip, unzip it and iron the coil flat on the back so the stitching can sit close to the teeth.
5. Sew one side, from the top down to the bottom stop. Then close the zip, check the waist seam lines up on both sides, and mark the second side before sewing it the same way.
6. Close the seam below the zip. For an invisible zip, switch to a regular zipper foot and stitch the remaining seam from where the zip stitching ended.
7. Restitch the lining or facing by hand with small slip stitches, using your photos as a guide.
8. Press again from the outside with a pressing cloth.

Expect 90 minutes to 2 hours the first time. The second dress takes half that. If you are nervous, practise on a charity shop skirt first; a 4 pound skirt is a cheap way to learn where the fabric wants to pucker before you touch a dress you care about.

Common mistakes and how to avoid them

• Uneven waist seams. Always check alignment after sewing the first side. Mark both sides of the seam on the zip tape with chalk.
• Puckering. Usually caused by stretching the fabric while sewing. Let the machine feed the fabric; do not pull it.
• A gap at the top. Stitch the top end of the tape at a slight angle away from the teeth so the slider can move freely past the waistband.
• Wrong length. A zip 2 to 3 cm longer than needed is fine; shorten from the bottom with a few hand stitches across the coil. A shorter one is not.

Replacing a zip is a good next step after you have learned how to mend a hole in a dress so it lasts. Both repairs stretch the life of clothes and lower their cost per wear far more than any new purchase. When you shop again, check zips at the till; our guide to spotting a well made dress explains what a good one looks like.

Frequently asked questions

How much does it cost to replace a zip in a dress?

Doing it yourself costs about 2 to 4 pounds for a new zip and thread. A tailor or alterations shop usually charges between 15 and 35 pounds depending on the dress, lining and zip type. Lined formal dresses are at the top of that range.

Can you fix a zip that keeps separating?

Often, yes. A zip that splits open behind the slider usually has a worn slider rather than damaged teeth. Squeezing a metal slider gently with pliers or fitting a replacement slider fixes most cases in minutes.

Can I replace a dress zip without a sewing machine?

Yes. Use a small backstitch with strong polyester thread, keeping stitches about 3 mm long and close to the teeth. It takes longer but can look neater than machine stitching on delicate fabrics.