To hem jeans and keep the original hem, fold the leg up to the outside so that the original hem's stitching line sits half the shortening amount below the fold, stitch right against the edge of the hem with a zipper foot, then trim the excess, finish it and press it up inside the leg. From the outside the jeans show the same faded, chain-stitched hem they had before, with one fine seam hidden in the shadow above it. The method takes about half an hour for a pair and works for anything from 2 to 10 cm (3/4 to 4 in) of shortening.

Why keep the original hem instead of sewing a new one?

A factory jeans hem is sewn with heavy gold or tan thread, often with a chain stitch that twists slightly in the wash and makes the hem "rope". The denim along the fold has faded with wear. A new hem sewn at home with all-purpose thread rarely matches it, and buying the right topstitching thread, a 100/16 needle and the patience to go over the bulky seams is more work than keeping what is there.

Keeping the hem is sometimes called a Euro hem or a tailor's hem. The technique is the same whatever the name: the leg is shortened by taking a tuck above the hem, and the tuck disappears inside.

What you need to hem jeans with the original hem

  • A jeans needle, 90/14 or 100/16 (a universal needle of that size works on light denim)
  • All-purpose polyester thread in a color close to the denim, not the gold topstitching: the seam is hidden
  • A zipper foot or an edge-stitching foot
  • A tape measure, tailor's chalk, pins or clips
  • Small scissors, a seam ripper, and a hammer or a folded piece of card to level the bulky seams
  • An iron, a press cloth and, ideally, a tailor's ham for pressing the round of the leg

How much should you shorten the jeans?

Put the jeans on with the shoes you will wear them with. Fold the bottom of each leg under until the length is right and pin the fold at the front and the back. Take them off and measure from the bottom edge of the hem to the pin: that is your shortening amount, call it X. Check both legs; they are often a few millimeters apart from the factory, and you want the same X on both. Round X to the nearest 5 mm (1/4 in).

Now measure the depth of the existing hem, from the bottom edge to the line of topstitching. On most jeans it is 1.2 to 1.5 cm (1/2 to 5/8 in). You will not need the number, but you need to know where that stitching line is, because every measurement in the next section starts from it, not from the bottom edge.

Tip: On tapered or skinny jeans, check the leg circumference at the hem and at X above it. If they differ by more than 1.5 cm (5/8 in), the join will pucker; a regular hem is the better choice for a large shortening.

How do you hem jeans and keep the original hem, step by step?

  1. Mark the fold line. Turn the jeans right side out. On each leg, measure up from the hem's stitching line by half of X and make a chalk mark at the inseam, the outseam, the center front and the center back. For a 6 cm (2 3/8 in) shortening, the marks sit 3 cm (1 1/8 in) above the stitching line.
  2. Fold the hem up to the outside along the marks, so that the original hem lies against the right side of the leg and the fold runs level around the leg. Match the inseam to the inseam and the outseam to the outseam first, then clip or pin every 5 cm (2 in). Check the fold: the distance from the fold to the hem's stitching line should be X/2 all the way round.
  3. Stitch beside the hem. Fit the zipper foot and move the needle so it runs in the groove between the rolled edge of the original hem and the leg, as close to the hem as possible without sewing on it. Use a 3 mm stitch. Start at the inseam, sew once around the leg and overlap the start by 2 cm (3/4 in). Slow down over the two thick seams; tap them flat with a hammer first and use folded card behind the foot to keep it level.
  4. Check before cutting. Unfold the leg. The original hem now hangs below the new seam, with a tube of excess fabric folded above it. Measure the leg from the waistband, compare the two legs, and try the jeans on. A seam ripper and five minutes fix a mistake now; after trimming they do not.
  5. Trim the excess. If the tuck is deeper than 1.5 cm (5/8 in), trim it to 1 cm (3/8 in) from the stitching. For a small shortening of 3 cm (1 1/4 in) or less, leave the tuck whole; it is barely wider than a seam allowance. Finish the cut edge with a zigzag or a serger, because denim frays.
  6. Press. Press the allowance up toward the knee with steam and a press cloth, then press the hem down from the outside so the fold sits sharp. On the outside you now see the original hem with a faint ridge above it.
  7. Secure the allowance, optionally. A line of stitching in the ditch of the new seam, or 2 mm (1/16 in) above it in matching thread, keeps the allowance from rolling down in the wash. On stretch denim it is worth doing; on rigid denim pressing alone usually holds.

Wash and press the jeans once more. The ridge softens and the join becomes hard to find.

What are the common mistakes when hemming jeans this way?

  • Measuring from the bottom edge instead of the stitching line. The jeans come out about 3 cm (1 1/4 in) shorter than planned, twice the depth of the hem. Measure from the topstitching.
  • Stitching on the hem rather than beside it. A second line of stitching shows on the outside and the hem no longer looks original. Keep the needle in the groove.
  • Matching the seams loosely. If the inseam of the hem lands 1 cm away from the inseam of the leg, the tuck twists and the hem sits crooked.
  • Sewing the thick seams at full speed. Four to eight layers of denim break needles. Hand-walk the machine over them.
  • Trimming before trying on. See step 4.
  • Skipping the pressing. Without steam the join rolls outward and looks like a turned-up cuff.
  • A large shortening on tapered legs. The leg is wider at the join than the hem, and the difference shows as a lip. Ease up to 1.5 cm of difference; beyond that, sew a new hem.

When should you sew a regular hem instead?

A regular double-fold hem of 1.2 cm (1/2 in) with topstitching thread is the better choice when you shorten tapered jeans by more than about 10 cm (4 in), when the original hem is frayed or stained and you wanted to lose it anyway, when you want a different finish such as a raw edge or a deep cuff, and on flared jeans, where the hem is wider than the leg above it and the join sags. The hemming guide covers the double-fold hem, and sewing with denim explains the needle, thread and stitch length that make the gold topstitching look right. If the layers at the seams stop your machine, sewing machine for denim and canvas lists the features that help.

Sewly does not draft jeans with a fly front yet; its pull-on trousers have the hem allowance already added to the pattern, so a pair made from scratch never needs this trick. It is for the jeans already in your wardrobe, bought a size longer because the length was never quite right.