Measure and mark your hem line before you cut

The most common mistake is cutting the fabric before you know exactly where the hem should be. Put on the dress with the shoes you plan to wear it with, and have someone measure from the floor to where you want the hem to end—usually 1/2 inch to 1 inch above the floor depending on the style. Mark this line all the way around the dress with tailor's chalk or a fabric pencil, stepping down carefully so the marks stay level.

Once marked, take off the dress and lay it flat on your work surface. Measure from the hem line to the raw edge of the fabric and add 1/2 inch for the fold. This total is how much fabric you need to turn up. For example, if you want a 1-inch finished hem, you'll fold up 2 1/2 inches of fabric (1 inch for the hem itself, plus 1 inch for the fold, plus 1/2 inch extra). Cut along your chalk line with sharp fabric scissors.

Key Takeaways

  • Always mark your hem while wearing the dress with the correct shoes, because the length changes based on your footwear and posture.
  • Fold the raw edge up 1/2 inch first, press it with an iron, then fold the hem to your desired width and press again before sewing.
  • Use a straight stitch on your machine with matching thread, sewing 1/4 inch from the inner fold of the hem for a find, invisible finish.
  • Test your stitch tension on a scrap of the same fabric first, because loose tension will cause puckering and tight tension can break the thread.
  • Sew slowly and use a walking foot if your machine has one, especially on stretchy fabrics like jersey or knits that tend to shift under the presser foot.

Press the fabric to set your fold lines

Fold the raw edge of the fabric up 1/2 inch and press it with a hot iron set to the appropriate temperature for your fabric. Check the dress label—cotton and linen can take a high heat, but synthetics and blends need medium heat. This first fold seals the raw edge and keeps it from fraying, and the crease helps you fold the hem evenly.

Now fold the hem up to your marked line and press again. The iron does the work here; you're not trying to flatten it with force. Let the heat set the crease, then let the fabric cool before you move it. A well-pressed hem is much easier to sew straight because the fold stays exactly where you put it.

Thread your machine and test on scrap fabric

Use thread that matches your dress fabric as closely as possible. If you can't find an exact match, choose a shade slightly darker rather than lighter—it's less visible. Wind a bobbin with the same thread and insert it into your machine according to your manual. Thread the needle, and make sure both the top thread and bobbin thread are seated properly in the tension discs, or your stitches will be loose and puckered.

Cut a scrap of the same fabric as your dress, fold it the same way you folded the hem, and sew a test line. Check the tension by looking at both sides of the stitching. The top thread and bobbin thread should lock together in the middle of the fabric layers—you shouldn't see loops on either side. If the top thread is loose, increase tension slightly. If the bobbin thread shows on top, decrease tension. Make small adjustments (usually one number at a time on the dial) and test again.

Sew the hem with a straight stitch

Set your machine to a straight stitch with a stitch length of 2.0 to 2.5 millimeters. This is slightly longer than a regular seam, which makes the stitching less likely to pucker on a fold. Position the dress under the presser foot so the needle will sew 1/4 inch from the inner fold of the hem—this keeps the stitching hidden when the hem is folded down.

Lower the presser foot, take a few stitches forward, then backstitch to lock the thread. Sew slowly around the entire hem, keeping the fabric edge aligned with the 1/4-inch mark on your presser foot plate (most machines have these guides). Stop every 6 to 8 inches to check that your fold is still even and your stitching is staying parallel to the edge. When you reach the starting point, overlap your stitches by about 1/2 inch and backstitch to finish.

Use a walking foot for stretchy or slippery fabrics

If your dress is made of jersey, knit, satin, or any fabric that shifts under the presser foot, attach a walking foot to your machine. This foot has its own feed dogs that grip the top layer of fabric while the machine's feed dogs move the bottom layer, so both layers move at the same speed. Without it, the top layer often creeps forward and creates an uneven hem.

A walking foot is an optional attachment that costs between $20 and $40 and works on most machines. Check your manual to see if your machine is compatible. If you don't have one and your fabric is slippery, sew very slowly and use your hands to gently guide the fabric—don't pull it, just steady it so it doesn't shift.

Press the finished hem and check for puckering

Once you've sewn all the way around, press the hem one more time with your iron. This sets the stitching and removes any wrinkles from handling. Press from the wrong side of the dress first, then flip it over and press from the right side. If you see any puckering along the stitch line, it usually means your tension was too tight. You can try loosening the tension and re-sewing a small section, or accept it as part of the learning process—most puckering smooths out after the dress is worn and washed a few times.

Try on the dress one more time to make sure the length is correct and the hem hangs evenly all the way around. If one side is slightly longer than the other, you can carefully unpick that section with a seam ripper, adjust the fold, and re-sew it. This is much easier to fix now than after you've worn the dress.

Frequently Asked Questions

What if I sewed the hem in the wrong place?

Use a seam ripper to carefully cut and remove the stitches. Pull the thread gently so you don't tear the fabric. Once the stitches are out, re-press the fabric to remove the old crease, re-measure and mark your new hem line, and sew again. The fabric may have small holes from the old stitches, but they usually close up after washing.

Can I use a serger instead of a regular sewing machine?

Yes, a serger creates a faster, more professional finish because it cuts the raw edge and wraps thread around it in one step. However, sergers are harder to control on a hem because they move so quickly. If you're new to hemming, start with a regular machine to learn the technique, then try a serger once you're comfortable.

Should I use a blind stitch instead of a straight stitch?

A blind stitch is designed to hide the stitching inside the fold so it's invisible from the outside. It's more advanced and requires practice to get right. A straight stitch 1/4 inch from the fold is just as strong and much easier to control, especially on your first hem. Once you're confident, experiment with blind stitch.

What if the fabric is too thick to fold twice?

On heavy fabrics like wool or denim, fold the raw edge up only 1/4 inch instead of 1/2 inch, press it, then fold the hem to your desired width. You can also finish the raw edge with pinking shears (which cut a zigzag pattern to prevent fraying) before folding, so you don't need the extra fold.

How do I know if my thread tension is correct?

Look at both sides of your test seam. If the stitching looks the same on both sides—a straight line of thread with no loops or loose spots—your tension is correct. If you see loops on the top, the top tension is too loose. If you see loops on the bottom, the bobbin tension is too loose (or top tension is too tight).