Measure and mark the new hem length before you cut

The first step is to figure out exactly where your new hem should sit. Put on the trousers with the shoes you plan to wear them with—heel height changes where the hem lands. Stand in front of a mirror and have someone else measure from the floor up to where you want the hem to end, or use a measuring tape yourself. The standard is about half an inch above the top of your shoe, but wear what feels right to you.

Once you know the length, put the trousers on inside-out and have your helper mark that line all the way around the leg with tailor's chalk or a fabric pen. Mark a second line about one inch below the first one—that extra inch is the part you'll fold up and stitch. This gives you a fold line and a cut line. Take the trousers off and try them on right-side-out one more time to double-check the mark looks even.

Key Takeaways

  • Measure with the shoes you'll wear the trousers with, and mark both a fold line and a cut line one inch below it.
  • Cut off the excess fabric along the lower line, then fold the fabric up along the fold line and press it flat with an iron before sewing.
  • Use a straight stitch on your machine set to medium length, and sew as close to the fold as you can without the needle hitting the fold itself.
  • Backstitch at the start and end of each seam to lock the thread, and try the trousers on before trimming any loose threads.

Cut the excess fabric and press the fold

Lay the trousers flat on a cutting surface with the inside-out leg stretched straight. Use fabric scissors or a rotary cutter to cut along the line you marked one inch below the fold line. Cut slowly and keep the blade perpendicular to the fabric so you get a clean edge. Do this for both legs.

Now fold the raw edge up to meet the fold line you marked. The wrong side of the fabric should be facing you. Use an iron on medium heat to press this fold flat. Press for a few seconds, lift the iron, and move along the leg. Do not slide the iron back and forth—that can stretch the fabric. Press the entire hem on both legs until it lies flat and holds its shape.

Thread your machine and set the stitch

Wind a bobbin with thread that matches your trousers. Thread the needle with the same color. If you cannot find an exact match, choose a shade slightly darker than the fabric—it will be less visible than a lighter thread.

Set your machine to a straight stitch with a stitch length of 2 to 2.5 millimeters. This is a medium length that holds well without creating a stiff seam. Test the tension on a scrap of folded fabric first. The thread should not bunch on either side, and the stitches should look even. Adjust the tension dial if needed—most machines have a dial numbered 0 to 9, and 4 or 5 is usually the default.

Sew the hem close to the fold

Place one trouser leg under the presser foot with the fold facing you. Position the needle so it will stitch as close to the fold as possible without actually hitting the fold itself—about one-eighth inch away. Lower the presser foot and backstitch three or four stitches to lock the thread. Backstitch means pressing the reverse button on your machine to sew backward.

Now sew forward along the entire hem, keeping the fold line as your guide. Sew slowly so you can keep the line straight. When you reach the end of the leg, backstitch three or four stitches again to lock the thread. Lift the presser foot, remove the trouser leg, and cut the thread. Repeat this process on the second leg.

Check the hem and finish the raw edge

Turn the trousers right-side-out and try them on. Walk around and sit down to make sure the length is correct and the hem lies flat. If the hem is uneven or the length is wrong, you can remove the stitches with a seam ripper and try again—this is normal and happens to everyone.

If the hem looks good, you can finish the raw edge to prevent fraying. Trim any loose threads with scissors. If you have a serger or an overlock machine, you can run the raw edge through it. If not, you can fold the raw edge under by about one-quarter inch and sew it down with a second line of stitching, or leave it as-is if the fabric does not fray badly. Cotton and linen fray more than synthetics, so this step matters more for natural fabrics.

Common mistakes to avoid

The most common error is measuring without the right shoes. A half-inch difference in heel height changes where the hem sits, and you cannot fix that after you cut. The second mistake is sewing too close to the fold—if your needle hits the fold line, it can skip stitches or break the thread.

A third mistake is pressing the hem without letting it cool. Fabric holds its shape better when the iron is removed and the fold is allowed to cool for a few seconds before you move it. Finally, do not rush the sewing. A slow, steady pace gives you straighter stitches and fewer mistakes than hurrying.

Frequently Asked Questions

Can I hem trousers without an iron?

You can, but the hem will not hold its shape as well while you sew. Without pressing, the fold may shift under the presser foot and create an uneven seam. If you do not have an iron, use a damp cloth and a hot pan or kettle to press the fold, or ask a friend to hold the fold in place while you sew very slowly.

What if my thread keeps breaking?

Check that the needle is inserted correctly—it should click into place and sit straight. Make sure the bobbin is wound evenly and threaded through the tension discs. If the thread is old or cheap, it may break more easily; try a new spool. Also check that you are not pulling the fabric while sewing—let the machine feed it through on its own.

How do I fix a crooked hem?

Use a seam ripper to cut and remove the old stitches. Press the hem flat again with an iron, re-mark the fold line if needed, and sew a new seam. It is faster than you think, and the second attempt is usually straighter because you know what to expect.

Should I use a special presser foot for hemming?

A standard presser foot works fine for hemming. Some machines have a blind-stitch foot that creates an invisible hem, but it requires a different stitch and takes more practice. Start with a straight stitch and a regular foot—once you master that, you can experiment with other methods.