A welt pocket is a slit in the garment finished with one or two narrow strips of fabric, the welts, with a pocket bag hanging behind. To sew a double welt pocket, interface the area, mark a rectangle 13 cm (5 1/8 in) long and 1.2 cm (1/2 in) high, sew two folded welt strips to its long edges with seams exactly 6 mm (1/4 in) apart, cut the rectangle open to the corners, push the welts through and sew the bag to them. Precision in marking matters more than any sewing skill: every line is drawn before the first stitch.

What is a welt pocket and which kinds are there?

A double welt pocket (also called a jetted or bound pocket) has two lips of equal width, 6 mm each, meeting in the middle of the slit. It is the pocket on the back of tailored trousers and inside a jacket. A single welt pocket has one lip, 2–3 cm (3/4–1 1/4 in) high, that covers the opening from below; it is the breast pocket of a jacket and the back pocket of chinos. A welt pocket with a flap is a double welt with a flap slipped in behind the upper lip.

All three share the same logic: a stitched rectangle, a cut, and strips pulled through to the inside. Once you have sewn the double welt, the others are variations.

What do you need to sew a welt pocket?

  • The garment piece, with the pocket line marked on the wrong side: a 13 cm (5 1/8 in) line for a trouser pocket, 11 cm (4 3/8 in) for a jacket breast pocket, with a short cross line at each end.
  • A patch of fusible interfacing 5 cm (2 in) bigger than the opening in every direction, fused to the wrong side of the garment.
  • Two welt strips from the garment fabric, cut on the straight grain, 4 cm (1 5/8 in) wide and the opening length plus 4 cm. Interface them too.
  • A pocket bag: two pieces of lining or pocketing, 16 cm (6 1/4 in) wide; one 14 cm (5 1/2 in) long and one 18 cm (7 in) long. On a visible pocket, a facing of garment fabric is sewn to the top of the longer bag so the fabric, not the lining, shows through the opening.
  • Chalk, a ruler, small sharp scissors, a 2 mm stitch length, and a pressing cloth.

Make a sample on a scrap of the same fabric first. A welt pocket cut in the wrong place cannot be undone; a sample costs ten minutes.

How do you sew a double welt pocket, step by step?

  1. Mark the box on the wrong side of the interfaced garment: the pocket line, a parallel line 6 mm above it and another 6 mm below, and the two end lines. The finished opening is 13 × 1.2 cm. Transfer the center line and ends to the right side with basting stitches so you can see them from both sides.
  2. Prepare the welts. Press each strip in half lengthwise, wrong sides together. Draw a line 6 mm from the fold on each, on the raw-edge side.
  3. Place the welts. On the right side of the garment, lay one welt with its raw edges on the center line and its fold pointing up; the drawn line on the welt sits on the upper box line. Lay the second welt below, raw edges meeting the first on the center line, fold pointing down. The two welts now cover the box, raw edges meeting in the middle.
  4. Sew the welts, one at a time, along the drawn lines, starting and stopping exactly at the end lines, backstitching two stitches. Turn the garment over and check from the wrong side: the two rows of stitching must be parallel, 1.2 cm apart, and the same length. If they are not, unpick now.
  5. Cut the opening. From the wrong side, cut along the center line, stopping 1 cm (3/8 in) from each end, then cut diagonally to the four corners of the stitching, ending one thread from each end stitch. The little triangles at the ends are the whole secret: cut too short and the corners pucker; cut through the stitches and the corner frays.
  6. Turn the welts through the opening to the wrong side. Press the triangles toward the inside, over the ends of the welts, and press the two welts so they meet along the center line. From the right side, the opening should now show two equal lips.
  7. Secure the triangles. Fold the garment back on itself at each end of the opening to expose the triangle lying on the welt ends, and sew across the base of the triangle, close to the fold, through the triangle and the welts. This squares the corners. Press from the right side under a cloth.
  8. Attach the pocket bag. Sew the shorter bag piece to the seam allowance of the lower welt, right sides together, from the wrong side; press it down. Sew the longer piece (with its facing) to the upper welt's seam allowance; it hangs down behind the first. Fold them together and sew around the sides and bottom of the bag with a 1 cm allowance, catching the triangles' seam again at the top. Finish the bag edges with zigzag or an overlock.
  9. Press the pocket from the right side with a pressing cloth, and baste the lips together with a diagonal hand stitch until the garment is finished, so they stay closed.

Every welt pocket is finished before the garment pieces are joined: on trousers, before the back is sewn to the front or the waistband goes on.

How do you sew a single welt pocket?

Cut one welt 7 cm (2 3/4 in) wide instead of two, interface it, and press it in half to 3.5 cm. Mark the box as above but 2.5 cm (1 in) high instead of 1.2 cm. Sew the welt's raw edges along the lower line only, with its fold pointing down, and sew the upper bag piece along the upper line, right sides together. Cut and turn as before: the welt flips up to cover the opening, the bag goes through behind it. Edgestitch or slipstitch the short ends of the welt to the garment, and finish the bag.

For a welt pocket with a flap, make the flap first (two layers, interfaced, turned and pressed, the width of the opening), and slip its raw edge behind the upper welt before step 8, so that it is caught in the seam with the upper bag.

Common mistakes with welt pockets

  • Skipping the interfacing. The fabric stretches as you cut and the corners wobble. Interface the garment area and the welts, always.
  • Stitching lines of unequal length. A difference of 2 mm shows as a corner that is higher on one side. Mark the end lines and stop on them.
  • Cutting the triangles short. The corners pucker because the fabric cannot turn. Cut to one thread from the end stitches, with the points of small scissors.
  • Welts of unequal width. Draw the stitching line on each welt before you place it instead of measuring from the fold with the foot.
  • Forgetting the facing on the bag. The lining shows through the opening every time it gapes. Face the top 5 cm (2 in) of the back bag with garment fabric.

When should you use a welt pocket instead of a patch or in-seam pocket?

A welt pocket is for garments where the pocket should be felt and not seen: the back of trousers, the inside of a jacket, the front of a coat, the hip of a straight skirt. It lies flat and adds no bulk at the edge of the garment. Use a patch pocket when the pocket is part of the design and the fabric is casual, and an in-seam pocket when a seam runs where you want the pocket and you want no visible opening at all.

The welt also suits fabrics that hold a press: wool, gabardine, twill, linen, cotton drill. On a loosely woven or very stretchy fabric, or a fabric that marks when unpicked, choose a patch or in-seam pocket instead. The seam ripper tutorial is worth reading before the first welt on velvet or silk, where every unpicked stitch leaves a trace.

If you are adding a welt to pull-on trousers drafted in Sewly, place the pocket line 6–7 cm (2 3/8–2 3/4 in) below the finished waistline on the back, centered between the side seam and the center back, and ask its sewing guide for the position on your own measurements. On any pattern, mark the pocket before cutting the fabric so that both backs are mirror images.