The basic steps to machine-hem pants
A machine-hemmed pair of pants starts with measuring how much fabric to fold up, then sewing a straight line around the leg opening. You fold the fabric up from the bottom, pin it in place, and run it under the presser foot of your machine in one continuous loop. The whole process takes 15 to 30 minutes per pair once you have the measurement right.
The reason most people use a machine instead of hand-sewing is speed and durability. A machine stitch holds tighter under the stress of walking and washing than hand stitches do, and it looks uniform. You do not need a fancy machine—a basic straight stitch is all that matters.
Key Takeaways
- Measure the desired length while wearing the shoes you will wear with the pants, standing on a flat surface, and mark both legs at the same height from the floor.
- Fold the fabric up to your marked line, pin it every inch or so, and press with an iron to crease the fold before sewing.
- Sew a straight line around the leg opening about a quarter-inch from the folded edge, keeping your seam parallel to the fold.
- Trim excess fabric inside the hem to about half an inch, then finish the raw edge with a zigzag stitch to prevent fraying.
Measure the pants while wearing them
Put on the pants with the shoes you plan to wear them with, and stand on a flat floor in front of a mirror. The hem should just touch the top of your shoe or sit a quarter-inch above it. Have someone mark that line with a fabric pencil or tailor's chalk on both legs—or mark one leg yourself, then sit down and mark the other leg at the same height.
The reason to wear the shoes is that different heel heights change where the hem sits. A half-inch difference in shoe height shifts the hem line noticeably. Mark both legs at the same distance from the floor, not the same distance from the crotch, because legs are not always the same length.
Once you have marked both legs, try the pants on again and look in the mirror. The hem line should be level when you stand straight. If one leg looks shorter, adjust the mark on that leg before you cut.
Fold, pin, and press the hem
Fold the fabric up along your marked line and pin it every inch or so around the leg opening. The pins should go through all layers and point toward the hem edge so you can remove them as you sew. Fold the fabric up on the inside of the pant leg, not the outside—you want the raw edge facing inward.
Once the hem is pinned all the way around, lay the pant leg flat on your ironing board and press the fold with a hot iron. Press along the entire folded edge, not just one spot. This crease holds the fabric in place while you sew and makes the finished hem look sharper. Let the fabric cool before you move it.
Check that the fold is even all the way around. If one section is higher or lower than the others, unpin that section, adjust it, and press again. A crooked fold will show in the finished hem.
Sew the hem with a straight stitch
Thread your machine with thread that matches the pants color. Use the same thread color on both the top and bobbin. Set the machine to a straight stitch with a stitch length of 2.0 to 2.5 millimeters—this is a standard length for most machines and holds well without looking too tight.
Place the pant leg under the presser foot so the needle will sew about a quarter-inch from the folded edge. Lower the presser foot, take a few stitches, then remove the pins as you go. Sew all the way around the leg opening in one continuous line, keeping the distance from the fold even. When you reach the starting point, overlap your stitches by about half an inch and cut the thread.
Sew slowly so you can keep the line straight. If your machine has a walking foot, use it—it feeds thick fabric more evenly than a standard presser foot. If you do not have one, go slowly and let the machine pull the fabric rather than pushing it yourself.
Trim and finish the raw edge
Turn the pant leg inside out and look at the hem from the inside. You should see your straight stitch line and the raw edge of fabric above it. Trim the excess fabric down to about half an inch above the stitch line using fabric scissors or a rotary cutter. Cut as close to the stitch as you safely can without cutting the thread itself.
Set your machine to a zigzag stitch and sew along the raw edge to prevent fraying. The zigzag does not have to be tight—a standard zigzag width of 2.5 to 3.0 millimeters works fine. This step keeps the hem from unraveling in the wash and makes the inside look finished.
If your fabric is very thick or prone to fraying (like denim or linen), you can also use pinking shears to cut the raw edge in a zigzag pattern instead of a straight line. Pinking shears do the same job as a zigzag stitch but take less time.
Press the finished hem and try them on
Turn the pant leg right-side out and lay it flat on your ironing board. Press the hem from the outside, running the iron along the fold line and then up the leg. This flattens the stitches and makes the hem sit smoothly. Press both legs the same way.
Put the pants on and look in the mirror. The hem should be level on both legs and sit at the height you marked. If one leg is noticeably shorter or longer, you can unpick that hem with a seam ripper and re-sew it. If the length is close enough, you are done.
Common mistakes and how to avoid them
The most common mistake is measuring without wearing shoes or without standing on a flat surface. Sitting down to measure, or measuring in socks when you will wear heels, leads to hems that are the wrong length. Measure standing up in the shoes you will actually wear.
The second mistake is not pressing the fold before sewing. A crease holds the fabric in the right place and makes the seam straight. If you skip the iron, the fabric shifts under the presser foot and the hem comes out wavy.
The third mistake is sewing too close to the fold. If your stitch line is right at the edge of the fold, the fold can roll under and the hem will look bunched. Sewing a quarter-inch away from the fold gives you room and makes the hem sit flat.
Frequently Asked Questions
Can I hem pants if the legs are different lengths?
Yes. Measure and hem each leg separately to the height that works for that leg. Some people's legs are genuinely different lengths, and hemming each one to the correct height is the only way to make them look even.
What thread color should I use?
Match the thread to the pants color as closely as you can. If the pants are a color that is hard to match, choose a thread one shade darker rather than lighter—dark thread shows less than light thread on dark fabric. Test on a scrap if you have one.
Do I have to zigzag the raw edge?
No, but it helps the hem last longer. If you skip the zigzag, the raw edge will fray over time, especially in the wash. For pants you wear often, the zigzag is worth the extra five minutes.
What if I sewed the hem crooked?
Use a seam ripper to cut and pull out the stitches, then press the crease out with an iron and damp cloth. Measure and pin again, and sew a new line. It is faster to redo it than to live with a crooked hem.
Can I hem stretchy fabric like knit pants?
Yes, but use a ballpoint needle instead of a standard needle—ballpoint needles slide between fibers instead of piercing them, which prevents runs. You can also use a stretch stitch if your machine has one, though a straight stitch works fine if you sew slowly and do not pull the fabric.