How to Hem Trousers (By Machine and By Hand)

Hemming trousers is the most useful sewing skill that almost nobody is taught. Half the population is wearing trousers that pool around their ankles or got chopped off badly at a dry cleaner’s, and the fix takes about half an hour at home. It’s also a brilliant first real project, because you’re improving something you wear rather than making a cushion cover destined for a drawer.

This guide covers the three hems you’ll actually use: a hand-sewn blind hem that disappears completely, a quick machine hem for casual trousers, and the trick for keeping the original factory hem on jeans so they still look like jeans.

Step one: get the length right

This is the part that matters most, and the part people rush. Put the trousers on, wearing the shoes you’ll usually wear with them. Heel height changes everything. Stand naturally in front of a mirror.

• For tailored trousers, the hem should sit with a slight break at the front of the shoe, just touching the top of it, and a fraction longer at the back.
• For casual trousers and chinos, a little shorter is fine and currently fashionable, sitting at or just above the top of the shoe.
• For jeans, it’s personal: a clean break, a small stack, or cropped at the ankle all work depending on the cut.

Fold the hem up to where you want it and pin it in place, then check both legs in the mirror. Mark the new fold line with chalk or a pin all the way round. Take the trousers off and measure to make sure both legs are identical. It’s astonishing how often one leg ends up a centimetre longer than the other.

Step two: work out the cut

Decide how deep you want the hem allowance (the bit folded up inside). For most trousers, 3–4cm is comfortable. Measure down from your new hemline by that amount and that’s where you cut, if you need to remove length. Always cut less than you think at first; you can trim more, but you can’t add it back.

Before cutting, unpick the original hem with a seam ripper so the fabric lies flat, then press the old fold out. Finish the raw cut edge so it won’t fray, either with an overlock or zigzag stitch, by folding under a small amount, or with pinking shears on fabric that frays little.

The invisible hand-sewn hem (blind hem)

This is what tailors use, and it’s invisible from the right side: no line of stitching shows. It’s hand sewing, but it’s quick and very forgiving.

1. Fold the hem up to your marked line and press it well. Pin it in place.
2. Thread a needle with a single thread that matches the trousers. Knot the end and anchor it inside the hem allowance so the knot is hidden.
3. Fold the top edge of the hem allowance back on itself slightly, so you’re working between the two layers.
4. Take a tiny stitch, just one or two threads, in the main trouser fabric, then a small stitch along the folded hem edge, alternating between the two. Keep the stitches loose and about 1cm apart.
5. The trick is to catch only a thread or two of the outer fabric each time. Catch too much and a dimple shows on the right side; catch too little and the hem won’t hold.

Because the stitches sit hidden in the fold and barely touch the outer fabric, the right side stays completely clean. This is the hem to use on anything smart.

The quick machine hem

For jeans, chinos, work trousers, and anything where a visible line of stitching is fine (or even wanted), a machine hem takes minutes.

1. Fold the hem up to your marked line and press. For a clean finish, fold in two stages, a small fold to enclose the raw edge and then up to the hemline, so no raw edge shows inside.
2. Pin from the right side, and sew from the right side too, so your topstitching looks neat where it shows. Sew close to the upper folded edge, working slowly around the leg.
3. Use the free arm of your machine if it has one. Slide the trouser leg over it like a sleeve so you’re not sewing the leg shut by accident.

On jeans, use a thicker topstitching thread (often a gold or contrast colour) to match the original, and go slowly over the side seams where the fabric is thick. A hump-jumper (a small plastic levelling tool) or a folded scrap of fabric tucked under the back of the foot keeps the needle from jamming as it climbs the thick seam.

Keeping the original hem on jeans

If you love the worn, faded look of an original jeans hem, you can shorten the leg without losing it. This method keeps the factory hem exactly as it is.

1. Work out how much length you need to remove and halve it. That number is your fold depth.
2. Fold the bottom of the jeans up on itself by that amount, so the original hem sits up the leg, with the existing stitched hem as the new folded edge. The faded factory hem now points down at the bottom.
3. Sew a new line of stitching just above the original hem, around the whole leg, securing the tuck. Use thread matching the denim so this new line hides.
4. Trim the excess fabric inside if needed, press the tuck upward, and the original faded hem sits at the bottom exactly where it always did, just higher up the leg.

From the outside, it looks like the jeans were always that length. It’s the single best trick for shortening good denim without it looking hemmed.

Common mistakes

• Hemming without the right shoes on. The length will be wrong the moment you change footwear.
• Cutting before checking both legs match. Measure twice. Trousers are rarely perfectly even to start with.
• Pulling thick denim seams through the machine. Slow down and use a levelling tool. Forcing it breaks needles.
• Skipping the press. A well-pressed fold is half the job. A hem you’ve pressed crisply almost sews itself.

Do one pair this weekend

Hemming trousers is the most immediately rewarding thing you can learn to do with a needle, because you wear the result the same day. Get the length right with your real shoes on, press everything, and pick the hem to match the trousers: a blind hem for smart, a machine hem for casual, the fold trick for good jeans. Do one pair this weekend and you’ll never pay for alterations again.