Measure and Mark Your Hem Line

Start by putting on the jeans and having someone measure from the floor to where you want the hem to sit — usually just touching the top of your shoe. Mark that spot with a fabric pencil or tailor's chalk while wearing the jeans. Take them off and measure the same distance from the floor on the inside leg seam, then mark all the way around both legs at that height.

The key is measuring from the floor, not from the waistband, because jeans naturally sit at different heights depending on how you wear them. If you measure from the waist, one leg will end up longer than the other. Mark both the front and back of each leg — you need at least three reference points per leg to keep the line level.

Key Takeaways

  • Measure from the floor while wearing the jeans to find the correct hem height, then mark that line with fabric pencil on both legs.
  • Try on the jeans before cutting to confirm the marked line is level and sits where you want it, because you cannot undo a cut.
  • Use a straight stitch set to medium length (2.5 to 3.0 on most machines) and sew parallel to the original hem, not over it.
  • Fold the raw edge under and topstitch it down in a second pass to match the original double-stitched look of store-bought jeans.
  • Test your tension and stitch length on a scrap of denim folded to the same thickness before hemming the actual jeans.

Try On and Verify the Hem Line

Put the jeans back on and look in a mirror from the front, back, and sides. The marked line should be level — if one side dips lower, adjust that mark before you cut. Have the person who helped you measure double-check from behind, because the back of jeans often sits slightly lower than the front. This is your final note to change your mind without wasting fabric.

Walk around in the jeans for a minute to make sure the length feels right when you move. Sit down and check that the hem does not bunch or pull. Once you are satisfied, take them off and lay them flat on your work surface with the inside facing up.

Cut and Prepare the Fabric

Using sharp fabric scissors, cut along your marked line on both legs. Cut straight across — do not angle the scissors or follow the original hem. You are removing the old hem entirely, so cut about one-quarter inch below your marked line to account for the fold you will make next.

Fold the raw edge up one-quarter inch and press it with an iron set to medium heat. Then fold it up again another one-half inch and press that fold as well. This double fold hides the raw edge and creates the structure for your new hem. The pressed creases will guide your stitching and keep the hem from shifting while you sew.

Set Up Your Sewing Machine

Thread your machine with thread that matches your jeans — usually dark blue or black. Use a needle size 16/100 or 18/110, which is heavy enough for denim without breaking. Denim is thick, so a standard needle may skip stitches or bend. If your machine has a denim or heavy-fabric setting, use it; if not, just slow down your sewing speed.

Set your stitch length to 2.5 to 3.0 — longer than you would use for regular fabric, because denim is dense and long stitches hold better. Test your tension and stitch on a scrap of denim folded to the same thickness as your hem (four layers). The stitches should look even on both sides with no loops or puckering. Adjust tension if needed before you start on the actual jeans.

Sew the First Seam Parallel to the Fold

Place the jeans under the presser foot with the folded hem facing up. Position the needle so it will stitch about one-eighth inch from the fold — this is the line that will show on the outside of the jeans. Lower the presser foot and begin sewing slowly, keeping the fold edge aligned with a guide mark on your machine's throat plate (most machines have lines marked at regular intervals).

Sew all the way around the first leg, then pivot at the seams and continue. When you reach the inside seam, you may need to lift the presser foot and reposition the jeans to keep the hem flat. Backstitch at the beginning and end of each seam to lock the thread. Remove the jeans and trim any loose threads.

Add the Topstitch for a Finished Look

The original hem on store-bought jeans has two visible rows of stitching on the outside. To match that look, fold the hem down and press it again so the fold is crisp. Sew a second seam about one-quarter inch below the first seam, again with the jeans inside-out so you can see and follow your first stitching line.

This second seam is what you see from the outside of the jeans. Keep it parallel to the first seam and use the same stitch length. When you finish both legs, try on the jeans to check the length and make sure both legs are even. If one side is slightly longer, you can add a third row of stitching on that leg only, or carefully remove stitches and re-sew if the difference is more than one-quarter inch.

Common Mistakes to Avoid

The most common error is sewing over the original hem instead of removing it first. The old hem is bulky and will create an uneven line. Always cut it off completely. Another mistake is not testing your tension on a scrap first — denim breaks needles and jams machines if the tension is wrong, and you will not know until you are halfway through a leg.

Do not rush the pressing step. Creases from the iron hold the fold in place while you sew and prevent the hem from shifting. If you skip pressing, the hem will ripple and your stitching line will waver. Finally, do not assume both legs are the same length — always measure from the floor on each leg separately, because one leg may naturally sit slightly lower than the other.

Frequently Asked Questions

Can I hem jeans if I have never used a sewing machine before?

Yes, but practice on a scrap of denim first. Sew a few inches to get a feel for how fast the fabric moves and how to keep a straight line. Jeans are actually forgiving because the thick fabric does not pucker easily. Take your time, sew slowly, and you will do fine.

What if my sewing machine keeps skipping stitches?

Change to a size 16 or 18 needle — a regular needle is too small for denim. Also check that the needle is inserted correctly (flat side facing the right direction for your machine) and that the thread is fully seated in the tension discs. If skipping continues, your machine may need cleaning or servicing.

Do I have to sew two rows of stitching, or can I just do one?

One row of stitching will hold the hem, but two rows match the original factory finish and look more professional. If you only sew one row, place it about one-quarter inch from the fold so it is visible from the outside.

What thread color should I use if my jeans are a light wash?

Match the thread to the jeans as closely as possible. For light blue jeans, use light blue thread. For very light or white denim, use white or off-white. Thread that contrasts with the fabric will be visible on the outside, so the closer the match, the better the hem looks.

Can I hem stretch jeans the same way as regular denim?

Stretch jeans need a slightly different approach because the fabric moves. Use a stretch needle (size 75/11) and a stretch stitch if your machine has one, or use a narrow zigzag stitch instead of a straight stitch. This allows the hem to flex with the fabric instead of breaking when you sit or move.