Measure and mark the correct length before you cut
Put on the slacks with the shoes you will wear them with, and have someone measure from the floor to where you want the hem to fall — usually about half an inch above your shoe. Mark that length on both legs with tailor's chalk or a fabric pencil, going all the way around each leg. The hem should be parallel to the floor, not angled.
Try the slacks on again and look in a mirror to confirm the length looks right. This step takes an extra five minutes and saves you from cutting too short. Once you cut fabric away, you cannot add it back.
Key Takeaways
- Measure the correct length while wearing the shoes you will pair with the slacks, and mark both legs with tailor's chalk before cutting.
- Cut the fabric straight across, leaving one and a half to two inches of material below your marked line for the hem allowance.
- Fold the raw edge up a quarter inch and press it with an iron, then fold the entire hem allowance up and press again to create a crisp crease.
- Sew the fold closest to the leg using a straight stitch or blind stitch, keeping your stitches parallel to the fold and about one-eighth inch from the edge.
- Press the finished hem flat with an iron to set the stitches and remove wrinkles before wearing the slacks.
Cut the fabric straight and leave enough material for the fold
Cut along your marked line with sharp fabric scissors, cutting straight across both legs. You need to leave one and a half to two inches of fabric below the cut line — this is your hem allowance, the part that will fold up and be sewn. If you cut too close to your marked line, you will not have enough material to work with.
A common mistake is cutting the legs at different lengths. Double-check that both legs are the same distance from the floor before you start sewing.
Press the raw edge and then the full hem fold
Fold the raw edge of the fabric up a quarter inch toward the inside of the leg and press it flat with an iron on medium heat. This folded edge will be hidden inside the hem and keeps the raw threads from showing or fraying.
Now fold the entire hem allowance up and press it again. If your hem allowance is one and a half inches, the fold should be one and a half inches up from the bottom of the leg. Press firmly so the crease is sharp and clear — this makes sewing much easier because the fabric stays in place under the presser foot.
Thread the machine and set your stitch
Thread your sewing machine with thread that matches the color of the slacks. Use a straight stitch or a blind stitch (also called a blind hem stitch). A blind stitch is harder to see from the outside of the leg, which is why tailors prefer it, but a straight stitch works fine and is simpler if you are new to sewing.
Set the stitch length to 2.0 to 2.5 millimeters — small enough to hold the hem securely but not so small that the thread bunches. Test the stitch on a scrap of fabric first if you are unsure about your settings.
Sew the hem fold to the leg
Place the leg inside the machine so you are sewing the fold closest to the leg — the fold you made second, not the raw edge fold. Keep your stitches parallel to the fold and about one-eighth inch away from it. Sew slowly and keep the fabric straight as it feeds under the presser foot.
Sew all the way around the leg, overlapping your stitches by about half an inch where you started and ended. Backstitch at the beginning and end to lock the thread. Repeat on the other leg.
Press the finished hem and try the slacks on
Press the finished hem flat with an iron to set the stitches and remove any wrinkles from the fold. Let the slacks cool for a minute before you move them, so the crease stays in place.
Try the slacks on and check that the hem hangs evenly and feels comfortable. If the stitches are visible from the outside and you do not like how they look, you can use a blind stitch next time — but many people find a straight stitch perfectly acceptable, especially on casual slacks.
Trim loose threads and check for puckering
Cut any loose thread ends with scissors. Look at the inside of the hem to make sure there are no puckers or bunches in the fabric. If the hem puckers, it usually means the fabric was stretched as it went under the presser foot — next time, guide the fabric gently without pulling.
If you see a small pucker, you can press it out with an iron and a damp cloth. Lay the damp cloth over the puckered area and press with medium heat for a few seconds, then let it dry.
Frequently Asked Questions
What if the hem is uneven after I sew it?
Uneven hems usually happen because the legs were not the same length when you marked them. You can fix this by carefully unpicking the stitches with a seam ripper, re-measuring both legs while wearing the shoes, and sewing again. It is worth taking the time to get it right.
Can I use a blind stitch if I have never sewn before?
Blind stitches are trickier than straight stitches because the needle moves side to side and you have to fold the fabric in a specific way. Start with a straight stitch to build confidence, then try a blind stitch on your next pair of slacks. Your machine manual will show you how to set it up.
What thread color should I use?
Match the thread to the color of the slacks as closely as you can. If the slacks are a dark color and you cannot find an exact match, choose a slightly darker thread rather than a lighter one — it will be less visible. You can also use neutral gray or black thread on most colors.
How do I know if my hem allowance is the right size?
One and a half to two inches is standard for most slacks. If you have very thick fabric, use two inches. If the fabric is thin or lightweight, one and a half inches is enough. The hem should not be so thick that it creates a bulge at the bottom of the leg.
Do I need to wash the slacks before hemming?
Yes, wash and dry them the way you normally would before you hem. Fabric can shrink, especially cotton, and hemming before washing means the hem might be too short after the first wash. Let the slacks dry completely before you measure and mark.