An invisible zip goes in before the rest of the seam is sewn. Open the zip, press its coils flat, then sew each tape to the right side of a seam allowance with the coil sitting on the seamline, stitching as close to the coil as an invisible zip foot allows, down to the slider. Close the zip and sew the seam below it with a regular zip foot, starting a little above and slightly outside the end of the zip stitching. From the outside you see only a seam and a small pull at the top.

The pattern pieces for size EU 38 / US 6, drawn by Sewly's drafting engine (seam allowances included). Shift dress →

What you need

  • An invisible zip at least 2 to 3 cm (1 in) longer than the opening, because the slider and the bottom stop take up space. Sewly lists the zip length in each pattern's notions: for example 20 cm (8 in) for skirts with a waistband, 22 cm (9 in) for the pencil skirt, 40 cm (16 in) for a back-zip top and 50 to 55 cm (20 to 22 in) for dresses.
  • An invisible zip foot. It has two grooves underneath that hold the coil upright so the needle can stitch right beside the teeth. Generic plastic feet fit many machines; check your machine's shank type.
  • A regular zip foot for closing the seam below the zip.
  • Fusible stay tape, or strips of lightweight fusible interfacing 2 cm (3/4 in) wide, for fabrics that stretch.

Prepare the seam

  1. Finish the raw edges of the zip seam on each piece separately, with a zigzag or a serger, before inserting the zip. Afterwards they are hard to reach. See finishing seams without a serger.
  2. Stabilize the opening on viscose, crepe, knits and anything cut off grain: fuse a strip of interfacing or stay tape to the wrong side of the seam allowance, covering the seamline, for the length of the zip. It stops the seam from rippling.
  3. Mark the seamline on the right side of each piece, usually 1.5 cm (5/8 in) from the edge, with chalk or a pressed crease.
  4. Mark the end of the opening. On Sewly patterns a notch on the seam shows where the zip opening ends. Snip it.
  5. Mark the top seamline, where a waistband, facing or neckline will be sewn later, so the zip can stop right below it.

Press the zip

Open the zip. From the wrong side, with the iron on a low synthetic setting (one dot, about 110 °C or 230 °F), press the coil so it unrolls and lies flatter, exposing the narrow groove between the coil and the tape. Do not press it closed, and never use a high temperature: nylon coils melt.

Sew the first side

  1. Position the zip. Lay the open zip face down on the right side of one piece, with the coil exactly on the seamline and the tape toward the raw edge. Place the top stop 2 to 3 mm (1/8 in) below the top seamline so the pull is not caught in the cross seam later.
  2. Pin or baste. Use pins parallel to the coil, or a strip of narrow double-sided basting tape on the zip tape. Hand basting is the most precise on slippery fabrics.
  3. Fit the invisible zip foot so the coil runs in one of its grooves and the needle stitches in the narrow space between the coil and the tape.
  4. Sew from the top down with a 2.5 mm stitch (about 10 stitches per inch), rolling the coil upright with your fingers ahead of the foot. Stop when the foot touches the slider, usually 2 cm (3/4 in) or so from the end of the zip. Backstitch.

Sew the second side

  1. Close the zip and lay the two pieces right sides together to check that the top seamlines line up. Mark on the free zip tape where the top seamline and any cross seams (a waist seam, a yoke) fall.
  2. Open the zip again and lay the second tape face down on the right side of the other piece, coil on the seamline, matching your marks. Check the zip is not twisted: the pull should face the right side of the fabric on both pieces.
  3. Sew from the top down with the coil in the other groove of the foot, stopping at the slider. Backstitch.
  4. Close the zip from the right side. It should disappear into the seam. If you can see teeth, sew that side again a hair closer to the coil.

Close the seam below the zip

  1. With the garment right sides together, pull the bottom end of the zip out of the way, toward the seam allowance.
  2. Switch to a regular zip foot.
  3. Start sewing 1 cm (3/8 in) above the end of the zip stitching and 2 mm (1/16 in) outside it, toward the raw edge, then sew down and gently rejoin the 1.5 cm (5/8 in) seamline. Backstitch at the start.
  4. Sew the rest of the seam. Press the allowances open below the zip, at the right heat for the fabric: about 200 °C (390 °F) for cotton and linen, 150 °C (300 °F) with a press cloth for wool and viscose, keeping the iron off the coil.
  5. Stitch the bottom ends of the zip tape to the seam allowances only, not to the garment, so they do not flap.
Tip: A small pucker at the bottom of the zip means there is a gap between the zip stitching and the seam stitching. Unpick the first 3 cm (1 1/4 in) of the seam and start again a little higher and closer.

Finish the top

The top of the zip tape is caught in the next seam: a waistband, a facing or a lining. Fold the tape ends toward the seam allowance at an angle so they do not show, and sew the cross seam right along the top seamline you marked. The pull then sits neatly at the edge with no gap above it.

How to shorten an invisible zip

Close the zip. Measure the length you need from the top stop and add 2 cm (3/4 in). Make a new stop at that point by hand, with several whipstitches over the coil, or by machine with a wide zigzag set to zero stitch length. Cut the zip 2 cm (3/4 in) below the new stop. Always shorten from the bottom; the top stops are fixed.

No invisible zip foot?

Use a regular zip foot with the needle moved as close to the coil as possible, after pressing the coil flat. Sew slowly and roll the coil away from the needle with your thumbnail as you go. The zip will not be quite as hidden, but in most fabrics the result is acceptable. Alternatively, choose a lapped zip, which is designed to be sewn with a regular zip foot.

Common mistakes and fixes

  • The zip shows. The stitching is too far from the coil. Sew again 1 mm (1/32 in) closer, with the coil pressed and held upright.
  • Cross seams do not line up. Mark the waist seam on the second tape before sewing it, and baste that side first to check.
  • The fabric waves along the zip. It stretched while sewing. Unpick, fuse stay tape, and sew again without pulling the fabric.
  • The slider will not pass. The needle caught the coil. Unpick that section and sew it again a hair further out.
  • The zip is too short for the opening. Close the seam higher, or replace it with a longer zip; never force the pull past the bottom stop.

For a first try, a skirt with a side or back zip is ideal, such as the pencil skirt or the A-line skirt. The invisible zip glossary entry explains how it differs from other zips.