Measure and mark your hem line before you sew
The first step is to figure out exactly where your new hem should be. Put on the pants with the shoes you plan to wear them with, and stand in front of a mirror. The hem should break slightly on top of your shoe — that means a small fold of fabric rests on the shoe, not a sharp crease. Have someone mark that line with tailor's chalk or a fabric pencil while you stand still, or do it yourself by pinching the fabric where it should end and marking both pant legs at the same height.
Take off the pants and measure from the original hem up to your new mark. Write this number down — it is the amount you will remove. Now measure from the cuff (the folded edge at the bottom) up about 2 inches and draw a straight line all the way around each pant leg with tailor's chalk. This second line is where you will cut. The 2-inch gap between your new hem line and the cut line gives you fabric to fold under and stitch.
Check both pant legs against each other. Lay them flat on a table and compare the distance from the cuff to your chalk marks on each side. If one leg is longer than the other, adjust the mark on the longer leg so both cuffs end at the same height from the ground.
Key Takeaways
- Measure your hem while wearing the pants with the shoes you will wear them with, and mark the line with tailor's chalk or fabric pencil.
- Cut the pant leg 2 inches below your desired hem line to leave fabric for folding and stitching.
- Use a straight stitch on your sewing machine set to medium length (2.5 to 3.0), and sew about 1/4 inch from the folded edge.
- Press the hem with an iron after sewing to set the fold and make the finished pants look professional.
- Try on the pants after hemming to check the length before cutting off any extra fabric.
Cut the fabric and prepare the fold
Cut along the chalk line you drew 2 inches below your desired hem. Use sharp fabric scissors and cut straight across, not at an angle. If the pant leg has a seam running up the inside, cut parallel to that seam so the cut edge stays even. After cutting, try on the pants again and check the length. This is your final note to adjust before you sew — if the length is wrong now, you will have to cut more fabric away, which means less room for the hem.
Once you are satisfied with the length, fold the raw edge up 1/2 inch toward the inside of the pant leg and press it flat with an iron on medium heat. This fold hides the raw edge and prevents fraying. Then fold that edge up again another 1.5 inches and press again. You now have a double fold — the raw edge is hidden inside, and you have a neat crease to sew along.
Thread your machine and set the stitch
Wind a bobbin with thread that matches your pants. If you cannot find an exact match, choose a color slightly darker than the fabric — dark thread is less visible than light thread in a seam. Thread the needle with the same color. Set your machine to a straight stitch with a stitch length of 2.5 to 3.0 — this is medium length, standard for hemming. Too short and the seam becomes stiff; too long and it will not hold the fold securely.
Test the tension on a scrap of fabric folded the same way as your hem. Sew a few inches and check that the thread is not bunching on either side. If the top thread shows on the underside, loosen the top tension slightly. If the bobbin thread shows on top, tighten the top tension. Make these adjustments in small steps — a quarter turn at a time — and test again.
Sew the hem on both pant legs
Slide one pant leg under the presser foot so the needle is about 1/4 inch from the folded edge of the hem. Lower the presser foot and sew forward slowly, keeping the fold lined up with the 1/4-inch mark on the needle plate (most machines have a line marked there). Sew all the way around the pant leg, stopping about 2 inches before you reach where you started. Backstitch to lock the thread, then remove the pant leg.
Overlap the end of your seam with the beginning by about 1/2 inch, lower the presser foot, and sew forward to close the gap. Backstitch again and cut the threads. Repeat this process on the second pant leg, making sure to sew at the same distance from the fold so both hems look identical.
As you sew, watch the fold, not the needle — your hands guide the fabric, and your eyes should track the edge you are trying to keep straight. If the fold starts to drift away from the 1/4-inch line, stop with the needle down, lift the presser foot, and adjust the fabric. Then lower the foot and continue.
Press the finished hem and check the length
Remove the pants from the machine and lay them flat on an ironing board. Set your iron to the heat setting for the fabric (check the care tag on the pants). Press the hem from the inside, pushing the iron along the seam to set the fold and flatten any puckers. Press from the outside as well, using a pressing cloth between the iron and the fabric if the material is delicate or prone to shine.
Try on the pants and check the length in a mirror. The hem should break evenly on both sides and sit at the same height on your shoe. If one side is longer, you can carefully unpick a few stitches, adjust the fold, and re-sew that section. If the hem is too short, you will need to cut more fabric away and start over, so measure carefully before you make any changes.
Common mistakes to avoid
The most common error is measuring the hem while wearing flat shoes and then wearing heels with the finished pants — the heel height changes where the hem sits. Always measure in the shoes you plan to wear. Another frequent mistake is cutting too much fabric away at once. If you remove more than 3 inches, you may not have enough fabric left to fold and sew a proper hem, especially on dress pants where the original hem is often narrow.
Sewing too close to the fold is another problem. If your stitches are right at the edge of the fold, the seam will be visible from the outside and the hem will look unfinished. Keep the stitches 1/4 inch away from the fold. Finally, do not skip the pressing step. A hem that is not pressed looks lumpy and unprofessional, even if the stitching is straight.
Trimming and finishing the raw edge
After you sew the hem, you can trim the excess fabric inside the fold if it looks bulky. Open the hem slightly and trim the raw edge down to about 1/4 inch from your stitching line. This reduces bulk, especially on heavy fabrics. You can finish the raw edge with a zigzag stitch to prevent fraying, or you can leave it as is — dress pants are usually worn long enough that the inside of the hem is never visible.
If you want a more polished look, run a zigzag stitch along the raw edge before you fold and sew the hem. Set your machine to a medium-width zigzag (about 2.5 to 3.0 width) and sew along the cut edge. This seals the edge and prevents unraveling, especially on fabrics that fray easily.
Frequently Asked Questions
Can I hem dress pants by hand instead of using a machine?
Yes, you can use a hand-sewing technique called a blind stitch, which is less visible than a machine stitch. However, a machine hem is faster, stronger, and holds up better to repeated washing and wearing. If you prefer hand-sewing, use a needle and thread that match your pants and make small stitches about 1/4 inch apart along the fold.
What if my sewing machine skips stitches or breaks thread?
Skipped stitches usually mean the needle is bent or inserted backward. Remove the needle, check it for damage, and reinsert it with the flat side facing the correct direction for your machine (check your manual). Thread breakage often happens because the presser foot is not raised when you thread the machine — the tension discs are only open when the foot is up. Raise the foot, rethread, and try again.
How much fabric should I leave for the hem fold?
A standard hem on dress pants uses 1.5 to 2 inches of fabric. Fold the raw edge up 1/2 inch, then fold it up again 1 to 1.5 inches. This double fold hides the raw edge and gives you enough fabric to sew securely without the hem being too thick or too thin.
Will the hem come undone if I wash the pants?
No, if you sew with a straight stitch and backstitch at the beginning and end, the hem will hold through many washings. Use thread that matches your pants and sew with medium stitch length — this creates a strong seam. Wash the pants inside out to reduce stress on the hem.
What if one pant leg is longer than the other after I sew?
Carefully unpick the stitches on the longer leg using a seam ripper, adjust the fold to make it shorter, and sew again. Start by unpicking just a few inches to see if that fixes the problem, rather than removing the entire seam at once. You can also try on the pants and have someone mark the correct length again before you re-sew.