Hemming pants on a sewing machine is straightforward once you measure correctly and practice the stitch
A sewing machine hem is stronger and faster than hand-sewing, and the straight stitch—the most basic machine stitch—is all you need. The real work happens before you touch the machine: measuring the right length, pinning the fold, and pressing it flat. If you get those steps right, the actual sewing takes about five minutes per pant leg. Most beginners succeed on their first try because the machine does the heavy lifting; your job is to feed the fabric straight and keep your hands clear of the needle.
This guide walks you through measuring, preparing, and sewing a basic hem. You will need a sewing machine, thread that matches your pants, a needle in the correct size for your fabric, pins, scissors, an iron, and a measuring tape. You do not need special presser feet or expensive tools.
Key Takeaways
- Measure the correct pant length while wearing the shoes you will wear with them, standing in front of a mirror, and mark the hem line with pins or chalk before cutting anything.
- Press the fold flat with an iron before sewing so the fabric stays in place and the stitch line is even.
- Use a straight stitch, thread color that matches your pants, and a needle size suited to your fabric weight—size 80/12 for lightweight cotton, size 90/14 for medium weight.
- Sew slowly and keep the fold aligned with a seam guide or tape on your machine bed so the stitch stays parallel to the hem edge.
- Test your stitch on scrap fabric first so you can adjust tension and stitch length before committing to your pants.
Measure the hem length while wearing the shoes you will wear
Put on the pants with the shoes you plan to wear them with, then stand in front of a mirror. The hem should just touch the top of your shoe or sit about half an inch above the ground. Have someone else measure from the floor to where you want the hem to end, or measure yourself by standing on a small step stool so you can see the back of your legs in the mirror.
Mark this length on both pant legs using pins placed horizontally across the inside of the leg, or use tailor's chalk to draw a light line. Mark at least three points on each leg—the inside seam, the outside seam, and the center front and back—so you can see if the line is level. Unpin or wipe away the chalk, then try the pants on again to confirm the marks are at the right height. This step prevents cutting too much fabric or ending up with uneven legs.
Once you are certain of the length, try the pants on one more time without shoes and sit down to make sure the hem does not pull or ride up. Sitting is when most people discover they measured too short.
Cut the excess fabric and fold the hem
Lay the pants flat on a table or ironing board with the inside facing up. Using your marked line as a guide, cut off the excess fabric, leaving about one inch below your mark. This one-inch tail will fold up to become the hem. If your original hem was already sewn, you can cut through that old stitch line and remove it with a seam ripper or small scissors.
Fold the one-inch tail up toward the inside of the pant leg and press it flat with your fingers. Then fold it up again so the raw edge is hidden inside the fold—this creates a double fold that looks finished and prevents fraying. The fold should now sit right at your original marked line. Pin this fold in place every two inches around the leg, keeping pins perpendicular to the fold so they do not get in the way of the presser foot.
Press the fold with an iron before sewing
Set your iron to the heat level for your fabric—check the care tag on your pants. Cotton and linen take medium to high heat; polyester and blends take low to medium. Lay the pant leg flat on your ironing board with the folded hem facing up, and press firmly along the entire fold for about 10 seconds. The heat sets the crease and helps the fold stay in place while you sew.
Let the fabric cool for a minute before moving it. A warm hem is still soft and can shift when you pick it up. Once it is cool, the fold should hold its shape without pins, though you can leave a few in place if you prefer extra security.
Set up your machine and test your stitch
Thread your machine with thread that matches your pants. If you cannot find an exact match, choose a shade slightly darker than the fabric—it will be less visible than a lighter shade. Wind a bobbin with the same thread and insert it into the bobbin case.
Set your machine to a straight stitch with a stitch length of 2.0 to 2.5 millimeters. This length is small enough to hold the fabric securely but large enough to see and remove if you make a mistake. Insert a needle in the size appropriate for your fabric: size 80/12 for lightweight cotton or linen, size 90/14 for medium-weight cotton or blends, and size 100/16 for heavier fabrics like denim or canvas. A needle that is too small will break; one that is too large will leave visible holes.
Cut a scrap of your pant fabric or similar weight fabric and fold it the same way you folded your hem. Sew a test line on this scrap, sewing slowly and keeping the fold aligned with the edge of your presser foot or a seam guide. Check the stitch: the top thread and bobbin thread should interlock in the middle of the fabric, not bunch on either side. If the stitch looks wrong, adjust the tension dial slightly—turn it up one number if the bobbin thread is showing on top, or down one number if the top thread is showing on the bottom—and test again.
Sew the hem with the fold facing up
Place the pant leg under the presser foot with the folded hem facing up and the fold aligned with the edge of the presser foot or a seam guide tape. Lower the presser foot and the needle into the fabric at the start of the fold. Sew slowly, keeping steady pressure on the fabric and watching the fold stay aligned with your guide. Do not pull or push the fabric; let the feed dogs move it under the needle.
Sew all the way around the pant leg, removing pins as you approach them. When you reach the starting point, overlap your stitches by about half an inch, then raise the presser foot and needle and cut the thread. Repeat this process on the other pant leg.
Once both legs are sewn, try the pants on to check the fit and the appearance of the hem. The stitch line should be straight and parallel to the edge of the fold, and the hem should hang evenly on both legs. If one leg is slightly longer or shorter, you can remove the stitches with a seam ripper and re-sew that leg.
Finish the raw edge if your fabric frays
If your pants are made of cotton or linen, the raw edge of the hem may fray over time, especially after washing. To prevent this, you can finish the edge with a zigzag stitch or a serger stitch if your machine has one. Set your machine to a zigzag stitch with a width of 2.0 to 3.0 millimeters and a length of 1.5 to 2.0 millimeters. Sew along the raw edge of the hem, letting the zigzag stitch go slightly off the edge so it catches and binds the fibers.
Alternatively, you can explore a thin strip of fusible hem tape along the raw edge before folding and pressing. This tape melts when heated and glues the raw edge down, preventing fraying without adding visible stitches. Follow the tape manufacturer's instructions for heat and pressure.
Frequently Asked Questions
What if my sewing machine skips stitches or breaks thread?
Skipped stitches usually mean the needle is bent, dull, or inserted incorrectly. Remove the needle, reinsert it making sure it clicks into place, and try again. If that does not work, replace the needle with a fresh one in the correct size for your fabric. Breaking thread often signals that the bobbin is wound too tightly, the presser foot is not raised when threading, or the tension is too high. Rewind the bobbin, raise the presser foot, and lower the tension dial one or two numbers.
Can I hem stretchy fabrics like knit or jersey?
Yes, but use a ballpoint needle instead of a sharp needle—ballpoint needles slide between fibers rather than piercing them, which prevents runs and laddering. You may also want to use a stretch stitch if your machine has one, or a narrow zigzag stitch instead of a straight stitch, because these stitches flex with the fabric. Test on a scrap first to see how the fabric behaves.
How do I fix a crooked hem after sewing?
If the hem is only slightly uneven, you can press it again and re-sew over the original stitch line, sewing more carefully this time. If it is very crooked or you want to start over, use a seam ripper to cut and remove the old stitches, then re-press and re-sew. Seam rippers have a small curved blade that slides under stitches without cutting the fabric.
Do I need to wash the pants before hemming?
Yes, if you plan to wash them after hemming. Fabric shrinks in the wash, and if you hem unwashed pants, the hem length will change after the first wash. Wash and dry the pants the way you normally would, then measure and hem them while they are still slightly damp so the fabric is relaxed and the measurement is accurate.
What thread color should I use if my pants are a color I cannot match?
Choose a shade slightly darker than the fabric. Dark thread is less visible than light thread because it blends into the shadows of the fold. If your pants are a very dark color like black or navy, use black thread. If they are a medium or light color, use a thread one shade darker than the fabric.