← Back to: Mastering the straight stitch, zigzag, and hem
It’s the classic one.
The moment you say you can sew—or worse, that you own a sewing machine—the request comes immediately:
“Could you shorten these jeans for me?
These trousers I bought on Vinted?
The little one’s cargo pants handed down from the older one?”
Trouser hems are the most requested alteration.
Good news:
If you can sew straight, keep a consistent seam allowance, and control your speed, you’ll be fine.
Take measurements
You should never measure trousers laid flat without trying them on first.
The trousers must be:
- worn
- adjusted to the actual waist
- tried on with the intended shoes
The height depends on the heel, the sole, and the look you want.
Take the time to confirm the length.
A 1 cm mistake shows immediately.
Calculate the length to remove
Measure the amount to remove from the existing hem.
Then you need to include the allowance needed to recreate a neat hem.
The double-fold method
For a clean hem, fold twice so there are no raw edges inside.
Allow for:
- 1.5 cm for the first fold
- 1.5 cm for the second
That’s 3 cm total.
Example
The trousers are 5 cm too long.
You need to remove:
5 cm – 3 cm = 2 cm
So you’ll cut off 2 cm of fabric.
Special case: very little length to remove
If the amount to remove is less than 3 cm:
- Do a single fold
- Overlock/serge the raw edge
- Subtract only 1.5 cm
Always adjust depending on:
- the fabric thickness
- the quality of the trousers
- the finish you want
Sewing is thinking before you act.
Transfer the measurement
Work precisely.
- Mark dots at the calculated distance
- Use chalk or an erasable pen
- Use a fine tip
Connect your dots neatly.
Check all the way around the leg that the distance is consistent.
Check both legs
Lay the legs on top of each other.
Compare the lengths.
Correct if needed.
Then cut off the excess.
Cut or not cut?
Yes, it’s best to remove the excess.
Why?
- Less bulk
- A cleaner hem
- A better finish
Special case: children’s trousers
If the garment needs to be able to be lengthened:
- Keep more fabric
- Increase the fold depth
Adapt to future use.
⚠️ After cutting, stack the legs again for a second check.
A double-check can save you.
Fold and prep
You’re now going to form the hem.
Two options:
- Overlock/serge, then fold once
- Fold twice (double fold)
The iron is essential
You press more than you sew.
Don’t iron it like laundry.
- Press with the hot iron
- Use steam
- Flatten the fold
If the fabric is delicate:
- Use a pressing cloth
- Or a cotton voile
Tip for a precise fold
If your fold is 1.5 cm:
- Place a strip of washi tape at 1.5 cm on the needle plate
- Sew a machine basting line (longest stitch possible)
- Don’t backstitch
This seam serves as a guide.
Fold to the wrong side, following this marker.
Once the first fold is pressed, the second fold forms naturally.
If needed:
- Sew a second basting line
- Fold again
- Press
- Pin perpendicular to the edge
Stitch the hem
Turn the trousers right side out.
It’s easier to sew from the right side, and the stitches look cleaner.
Stitching distance
- 1.5 cm fold → stitch at 1 cm
- 2 cm fold → stitch at 1.5 cm
Always adjust.
Recommended settings
- Matching thread (or contrasting, e.g., ochre for jeans)
- Needle suited to the thickness
- Slightly longer stitch length
Look at the trousers’ existing seams and match the original style as closely as possible.
Sewing method
- Start without backstitching
- Sew all the way around
- When you reach the start, sew back over 2 or 3 stitches to secure
Handling bulky seams
If the side seam creates a step:
- Clip the seam allowance slightly
- Press it to one side, then the other
- Reduce the bulk you have to sew over
Don’t force the machine.
Finishing
- Trim the threads
- Remove the basting threads
- Press the finished hem
Don’t say you know how to hem.
You might end up as the official alterations service for everyone you know.
