The basic steps for hemming a dress
To hem a dress on a sewing machine, you measure how much fabric to remove, fold and pin the new hem line, and then sew it with a straight stitch. The process takes about 30 minutes for a straightforward dress hem, though the time varies depending on how much of the dress you are hemming and whether you need to try it on partway through.
Start by putting on the dress and having someone mark where you want the new hem to fall—usually at your knee, mid-calf, or ankle, depending on the style. Use a fabric pencil, tailor's chalk, or pins to mark the line all the way around. Take the dress off and measure how far the current hem sits below your mark. That measurement is how much you will fold up.
Fold the fabric up along your marked line and pin it in place every 2 to 3 inches around the entire hem. Press the fold with an iron to crease it so it holds its shape while you sew. This crease is your guide—you will sew along it or just below it, depending on the hem style you choose.
Key Takeaways
- Mark the new hem line while wearing the dress, then measure how much fabric sits below that line to know how far to fold.
- Pin the folded hem every 2 to 3 inches and press it with an iron to create a crease that guides your sewing.
- A straight stitch sewn 1/4 inch from the folded edge is the most common choice for dress hems and works on most fabrics.
- Try on the dress after hemming to check the length before cutting away excess fabric, because mistakes are harder to fix once you trim.
- Lightweight fabrics may need a narrow hem or a rolled hem foot to prevent puckering, while heavier fabrics usually work fine with a standard straight stitch.
Choosing your stitch and thread
A straight stitch is the standard choice for most dress hems. Set your machine to a stitch length of 2.0 to 2.5 millimeters—long enough to hold the fabric but not so long that it looks loose or pulls the hem out of shape. Use thread that matches your fabric color as closely as possible. If you cannot find an exact match, choose a shade slightly darker rather than lighter, because it will be less visible.
For lightweight fabrics like cotton voile, linen, or silk, a straight stitch can sometimes cause puckering or a wavy edge. If this happens, try a narrow hem instead: fold the fabric only 1/4 inch instead of the usual 1/2 to 1 inch, and sew close to the fold. Some machines have a rolled hem foot that folds the fabric automatically as you sew, which works well for delicate materials.
For heavier fabrics like denim, canvas, or thick cotton, a standard straight stitch works reliably. You may need to slow down as you sew and use a needle one size larger than usual—a size 14 or 16 instead of a size 12—to push through the extra layers without breaking.
Pinning and pressing before you sew
Pinning holds the hem in place while you sew and prevents it from shifting. Place pins perpendicular to the fold—that is, pointing toward the body of the dress rather than along the hem line. Space them 2 to 3 inches apart all the way around. If the dress is very full or flared, you may need pins closer together to keep the hem from bunching.
After pinning, press the folded hem with an iron on the appropriate heat setting for your fabric. This crease serves two purposes: it holds the fold in place so pins alone do not have to do all the work, and it gives you a clear visual line to follow as you sew. Let the hem cool completely before you remove the pins and move to the machine.
If you are hemming a curved or flared hem, the fabric may not lie flat even after pressing. This is normal. Ease the fullness gently as you sew—do not pull the fabric, but let the machine feed it at its own pace. If you pull, the hem will pucker and the dress will not hang evenly.
Sewing the hem on the machine
Thread your machine and wind a bobbin in matching thread. Place the dress under the presser foot so the needle will enter the fabric about 1/4 inch from the folded edge of the hem. This distance is standard and creates a neat, find seam. Backstitch a few stitches at the start to lock the thread, then sew forward slowly and steadily.
Keep the fold of the hem aligned with the edge guide on your machine's throat plate, or use a seam guide if your machine has one. This helps you maintain an even distance from the fold throughout. Sew all the way around the dress, removing pins as you approach them—never sew over a pin, because it can break your needle or damage the machine.
When you reach the point where you started, overlap your stitches by about 1/2 inch, then backstitch to lock the thread. Trim the thread tails and remove the dress from the machine. Press the finished hem with an iron to set the stitches and give it a professional appearance.
Trimming excess fabric and finishing the raw edge
Before you trim, try on the dress and check that the hem hangs evenly and sits at the length you want. Look at it from the front, back, and sides. If the length is correct, you can trim the excess fabric. If it needs adjustment, you can unpick the stitches, re-pin, and sew again—this is much easier than trying to fix a hem after you have cut the fabric away.
Once you are satisfied with the length, trim the excess fabric to about 1/2 inch above your stitching line. Use sharp fabric scissors and cut slowly and carefully so you do not accidentally cut through the dress itself. If the raw edge of the fabric frays easily—as it does with cotton, linen, and many knits—you can finish it with a zigzag stitch, a serger, or pinking shears to prevent fraying over time.
A zigzag stitch is the simplest option if you do not have a serger. Set your machine to a medium-width zigzag and sew along the raw edge, letting the needle swing just over the edge of the fabric. This locks the fibers and prevents unraveling. Press the finished hem one more time and your dress is ready to wear.
Common problems and how to fix them
Puckered or wavy hem: This usually happens with lightweight fabrics or when you have pulled the fabric too tightly as you sewed. Unpick the stitches, re-press the fold, and sew again more slowly, letting the machine feed the fabric without tension from your hands. If it happens again, try a narrower hem or a rolled hem foot.
Uneven hem length: If one side of the dress hangs lower than the other, the dress itself may not be hanging straight—try it on and mark the new line again while wearing it. If the hem was marked correctly but still came out uneven, you may have eased the fullness unevenly as you sewed. Unpick and re-sew, paying attention to how the fabric feeds under the presser foot.
Skipped stitches or broken thread: This usually means your needle is dull, bent, or the wrong size for your fabric. Replace the needle with a fresh one in the correct size for your material. Check that your thread is wound smoothly on the bobbin and that both the top and bobbin thread are threaded correctly through all the guides.
Hem that comes loose after washing: This happens when the stitches are too loose or the thread is too thin. Use a stitch length of 2.0 to 2.5 millimeters and make sure your thread tension is balanced—the stitches should look the same on both sides of the fabric. If you are using very thin thread, try a slightly thicker weight.
Frequently Asked Questions
Do I need to remove the old hem before sewing a new one?
If the old hem is in good condition and sits above where your new hem will be, you can leave it. If it will show below the new hem or if the fabric is damaged, unpick it with a seam ripper before you start. Unpicking takes time but gives you a cleaner result and prevents bulk from multiple layers of fabric.
What if my dress has a curved or flared bottom?
Curved hems need more pins—place them 1 to 2 inches apart instead of 2 to 3 inches. Press the fold carefully and ease the fullness gently as you sew. The fabric will naturally want to bunch, so feed it slowly and let the machine do the work rather than pulling or pushing.
Can I hem a dress by hand instead of using a machine?
Yes, a hand-sewn hem using a slip stitch or ladder stitch is invisible and works well for delicate fabrics or hems that need to be very flexible. It takes longer—usually 1 to 2 hours depending on the dress length—but many people prefer the result for special garments.
How do I know if my needle is the right size for my fabric?
Needle sizes range from 60 to 120, with lower numbers for delicate fabrics and higher numbers for heavy ones. A size 70 or 80 works for most cotton and linen dresses, a size 60 or 70 for silk or lightweight knits, and a size 90 or 100 for denim or canvas. If your needle keeps breaking or skipping stitches, try going up one size.
Should I wash the dress before hemming?
Yes, if you plan to wash it after hemming. Fabric shrinks in the wash, and if you hem before washing, the hem may end up shorter than you intended. Wash, dry, and press the dress, then mark and hem it.