How to Hem Trousers: Machine, Hand and the Jeans Trick

Trousers come in three lengths: too long, much too long, and the pair you already hemmed. Hemming is the most useful repair skill there is — it is the difference between clothes that fit you and clothes that fit a person of average height who does not exist. It is also forgiving work, because a hem is a straight line on a flat edge and nobody inspects the inside of your ankle.

There are four honest ways to do it, and the right one depends on the trousers rather than on your skill level: a machine straight-stitch hem, a hand blind hem, the original-hem trick for jeans, and hem tape — including when tape is genuinely correct and not a shortcut to feel bad about. This is core Level 2 Stitcher territory.

Step one: measure with the shoes on

Almost every hem that goes wrong goes wrong here, before any stitching happens.

1. Put on the actual shoes you will wear with these trousers. Heel height changes the finished length more than anything else you will do today.
2. Stand normally on a hard floor. Do not stand up straighter than you live.
3. Fold the excess up on the outside and pin it at the front of one leg, at the length you want. Have someone check the back if you can — trouser legs usually want to sit slightly longer at the back.
4. Walk a few steps, sit down, stand up, check a mirror, adjust.
5. Pin all the way around that one leg, folding the excess up evenly.

Now take the trousers off, lay them flat, and measure how much you folded up. That single number — the amount removed — is what you transfer to the second leg. Do not re-pin the second leg on your body, because you will get a slightly different answer and end up with two different lengths.

The two numbers that matter

The amount removed is how much shorter the trousers get, measured from your pinned leg. The hem allowance is the fabric folded up inside the finished hem, and it is your choice. Together they give you the cut line: original hem edge, minus the amount removed, plus the hem allowance.

Mark the cut line all the way around with chalk or a fabric marker, using a ruler so your line stays parallel to the existing hem. Cut only after you have checked both legs match.

Unpicking the old hem

You need the old hem out before you can build a new one. Use a seam ripper, not scissors — scissors cut fabric as often as they cut thread.

• Work from the inside, sliding the point under every third or fourth stitch and cutting; once a run is loose, pull the thread out rather than cutting every stitch.
• Brush the loose thread ends out. They tangle in the new stitching if you leave them.
• Press the old fold flat and open before doing anything else. That crease is memory, and it will fight you.

Method 1: the machine straight-stitch hem

The workhorse. Visible stitching, fast, strong, and correct for jeans, chinos, work trousers and anything casual.

1. Fold the raw edge up by half your hem allowance and press.
2. Fold up again by the same amount, enclosing the raw edge entirely. Press again. This double fold is what stops fraying — no overlocker needed.
3. Pin from the inside, or better, press firmly enough that you barely need pins.
4. Sew from the inside leg seam so your start and stop meet somewhere inconspicuous, keeping an even distance from the folded edge.
5. Backstitch at the beginning and end, and trim the tails.

Method 2: the hand blind hem (slip stitch)

For suit trousers, dress trousers and anything where a visible line of machine stitching would look wrong. Slower, and genuinely better-looking. The stitch is the slip stitch, covered in basic hand sewing stitches:

1. Fold and press the hem allowance up as normal. Finish the raw edge first — fold under about a quarter inch, or zigzag it on the machine.
2. Fold the hem allowance back down on itself so about a quarter inch of the folded edge peeks out, and you are looking at the inside of the trouser leg.
3. Take a tiny stitch — one or two threads only — from the trouser fabric, then a longer stitch travelling inside the fold of the hem allowance.
4. Alternate. Keep the thread loose enough that it does not dimple the outside.

Only the tiny bites show on the right side, and in matching thread they disappear. Use a single thread, not doubled, and do not pull tight — a taut blind hem puckers into visible dots along the leg.

Method 3: keep the original hem (the jeans trick)

Jeans hems are made on industrial machines with heavy gold topstitching and a distinct faded wear line. Cut that off and the jeans look shortened. Keep it and they look like they came that way.

1. Work out how much shorter you want the jeans — the amount removed.
2. Fold the leg up on the outside so the original hem sits half the amount removed above the new finished length. Half, because the fold doubles.
3. Pin so the original stitching line is even all the way around, and check the leg has not twisted.
4. Sew a line just above the original hem's topstitching, through both layers, in ordinary matching thread. Keep it close and tidy.
5. Trim the excess inside to about half an inch and press the tuck upward.

The original hem is the bottom of the jeans again, with a small tuck hidden above it. The fade line and gold stitching survive intact.

Method 4: hem tape — when it is honestly fine

Fusible hem tape is a strip of adhesive web that bonds two layers together under a hot iron. It is not sewing, and it is not cheating either.

Good answer when: the trousers are a temporary fix (a costume, a growing child, a borrowed pair), the fabric is stable and mid-weight, or you do not own a machine yet and want them wearable tonight.

Wrong answer when: they will be washed often and hot, because bonds fatigue; the fabric is a fine wool suiting where adhesive stiffens the drape; or you want the alteration to be permanent.

Which method for which trousers

Pressing is half the job

If you take one thing from this guide, take this: a hem is made by the iron and merely secured by the thread. Every fold you press stays folded, feeds straight, and sews without pins fighting you.

• Press the old crease out before you measure, or it shadows through the new hem.
• Press each fold as you make it, not all at the end.
• Steam on cotton and denim; a pressing cloth on wool and synthetics so the iron does not leave a shine.
• Press means lift and set down. Shoving the iron along stretches the folded edge into a wave.

A steam iron with real weight does most of this for you; see irons for what to look for. A stable surface matters more than people expect, too — a soft or wobbly board makes crisp folds impossible, which is the whole argument for a proper ironing board over the kitchen table and a towel.

When the first hem is wonky

It will be, a bit. The stitching will wander somewhere, or one leg will end up a few millimetres shorter. Wear them. Nobody is measuring your ankles, and the second pair will be noticeably better than the first — that is how this works.