How To · Fashion · Alterations
How to Hem Trousers Like a Pro
A proper hem transforms an ill-fitting pair into something you'll actually reach for. Whether you're working with tailored wool or everyday cotton, this guide walks you through the essentials—no sewing machine required.
5 min read · IrisThe difference between trousers that fit and trousers that *work* often comes down to the hem. Too long and you're dragging fabric; too short and you've lost the proportion that makes business-casual actually casual. The good news: hemming by hand is a learnable skill that costs nothing and takes less than an hour.
This method uses a slip-stitch—the same technique tailors have relied on for decades. It's invisible from the outside, holds through washing and dry cleaning, and requires only a needle, thread, and patience. No machine. No special equipment. Just precision.
The slip-stitch is invisible from the outside and holds beautifully through years of wear.
What you'll need.
- 01Measuring tape
- 02Tailor's chalk or fabric pencil
- 03Sharp fabric scissors
- 04Iron and ironing board
- 05Hand-sewing needle (size 7 or 8)
- 06Thread matching your trousers
- 07Thimble (optional)
Step one · 5 minutes
Measure and mark the correct length
Put on the trousers with the shoes you'll wear them with—this matters. Stand in front of a mirror and have someone measure from the top of your shoe to where the hem should sit. The front of the trouser leg should just graze the top of your shoe, with a slight break in the fabric. Mark this length with tailor's chalk or a fabric pencil on both legs, all the way around. Double-check your work before cutting.
If you're hemming alone, use a full-length mirror and mark while standing naturally. Sitting changes the proportions.
Step two · 5 minutes
Cut the excess fabric
Add 1.5 inches to your marked line—this becomes your hem allowance. Cut along this new line with sharp fabric scissors, cutting straight across. Do this for both legs. A clean, straight cut is essential; jagged edges will fray and make stitching harder. If you're nervous, cut slightly less than 1.5 inches; you can always trim more later.
Cut on a flat surface with good lighting. Dull scissors will drag the fabric and create uneven edges.
Step three · 10 minutes
Fold and press the hem
Fold the cut edge up 0.5 inches and press with an iron on the appropriate heat setting for your fabric. Then fold that pressed edge up again by 1 inch and press again. You now have a double-folded hem that's sturdy and won't fray. The fold should be crisp but not scorched. Let the fabric cool before moving on.
Use a pressing cloth between the iron and delicate fabrics to avoid shine marks.
Step four · 2 minutes
Thread your needle and knot the end
Cut about 18 inches of thread—longer threads tangle and fray. Thread your needle and tie a single knot at one end. Use thread that matches your trousers as closely as possible; if you can't find an exact match, go slightly darker rather than lighter. A size 7 or 8 needle works for most fabrics.
Wet the thread end slightly to make it easier to pass through the needle eye.
Step five · 20 minutes
Stitch the hem using the slip-stitch
Start at an inside seam where the knot won't show. Bring the needle up through the fold of the hem, then slide it horizontally inside the fold for about 0.25 inches. Exit the fold and pick up just two or three threads of the trouser fabric directly above. Go back into the fold and repeat. Your stitches should be small (about 0.25 inches apart) and the thread should be snug but not tight enough to pucker the fabric. Work your way around the entire hem.
The slip-stitch works because the thread runs inside the fold—it's invisible from the outside. Take your time and keep stitches consistent.
Step six · 3 minutes
Finish and check your work
When you've stitched all the way around, take a small stitch in place, then bring your needle up through the fold one more time. Tie off with a small knot inside the fold and trim the thread. Try on the trousers and check the length in a mirror. The hem should be even, invisible from the outside, and feel secure when you move.
If one leg is slightly longer than the other, you can add a few stitches to adjust. Hemming is forgiving.
How to know it works
A successful hem is invisible from the outside, sits at the correct length, and doesn't shift or pucker when you move. The stitching should be secure enough to survive multiple wearings and dry cleanings without coming loose.
Questions at the mirror.
My stitches are showing on the outside. What went wrong?
You're likely picking up too much fabric from the trouser leg itself. The slip-stitch should only catch two or three threads of the outer fabric—barely a whisper. Unpick that section and try again with a lighter touch.
The hem is coming loose after one wear. Why?
Either your knot wasn't secure or your stitches are too far apart. Aim for stitches no more than 0.25 inches apart, and always tie a proper knot at the start and end. If it's already loose, simply re-stitch that section.
Can I use this method on stretchy fabrics like ponte or knits?
Yes, but use a slightly more flexible thread (like polyester) and keep your stitches small and consistent. Stretchy fabrics need extra security. Some people prefer a machine stitch for these, but hand-stitching works if you're careful.
How do I know if my hem allowance is enough?
A 1.5-inch allowance is standard and works for most trousers. If you're hemming something with a wider leg or unusual fabric, aim for 1.5 to 2 inches. You can always trim more, but you can't add back what you've cut.