A curved hem follows the shape of the fabric instead of a straight line
A curved hem is any hem that bends around a curve in the garment — the armhole of a sleeveless top, the neckline of a dress, the hem of a circular skirt, or the leg opening of pants. The challenge is that curved fabric wants to pucker or fold when you try to fold it flat, so you have to ease the fullness as you sew instead of pulling it tight.
The basic method is the same whether you sew by hand or machine: you fold the hem allowance to the inside, pin it in place while gently stretching the outer edge, and stitch close to the fold. The difference is in how much you stretch and how much patience you need. A machine hem on a gentle curve takes 10 to 15 minutes. A hand-sewn curved hem on a tight curve like an armhole can take an hour.
Key Takeaways
- Curved hems need a narrower hem allowance than straight ones — usually 1/4 inch to 1/2 inch instead of 1 inch — so the fabric has less bulk to fold.
- You must ease the fullness by gently stretching the outer edge of the curve as you fold and pin, or the hem will bunch on the inside.
- A machine works best on gentle curves like a circular skirt hem; tight curves like armholes are easier to hand-sew because you can feel the tension.
- Pressing the fold flat before you sew, and pressing again after, makes the hem lie smooth and keeps it from rolling.
Prepare the curve by trimming the hem allowance narrow
Start by deciding how wide your hem allowance should be. For a gentle curve — the hem of a full skirt or the leg of wide pants — a 1/2-inch allowance works. For a tight curve — an armhole or a neckline — trim it to 1/4 inch. The narrower the allowance, the less fabric you have to fold and ease, and the flatter the hem will lie.
Trim the seam allowance with sharp scissors or a rotary cutter, cutting parallel to the edge of the garment. If the curve is very tight, you can clip small notches into the allowance every 1/2 inch or so, cutting toward the stitching line but not through it. These notches let the fabric spread slightly on the inside of the curve, which reduces bunching.
Press the raw edge of the allowance with a hot iron to remove wrinkles. This makes it easier to fold and pin smoothly.
Fold and pin the hem while easing the fullness
Fold the hem allowance to the inside of the garment along the line where you want the hem to sit. On a curved edge, you cannot straightforward fold and pin straight — you have to ease the fabric as you go. This means gently stretching the outer edge of the curve (the edge farthest from the body of the garment) so that the inner edge folds smoothly without puckering.
Work in small sections, about 2 to 3 inches at a time. Fold the allowance, then use your fingers or a pressing tool to stretch the outer edge slightly while you pin. The pins should go through all layers — the allowance, the fold, and the garment body. Space them about 1/2 inch apart on tight curves, or 1 inch apart on gentle curves.
As you work around the curve, check the inside of the garment often. If you see small pleats or puckers forming, you have stretched too much or not enough. Unpin that section and try again with gentler tension. Once the whole curve is pinned, press the fold flat with a hot iron. This sets the ease and makes the hem much easier to sew.
Sew a curved hem by machine
A machine works well for gentle curves — a circular skirt hem, the leg opening of relaxed pants, or a curved waistband. Set your machine to a straight stitch with a stitch length of 2.0 to 2.5 millimeters. Use a thread color that matches the garment.
Sew close to the fold of the hem, about 1/8 inch away. Sew slowly and keep your hands relaxed — do not pull the fabric toward or away from the presser foot. The machine will feed the fabric at its own pace, and your job is just to guide it. If the fabric starts to bunch, stop, lift the presser foot, and unpin that section. Repin with less tension and try again.
Once you have sewn all the way around, press the hem flat from the inside. Then turn the garment right-side out and press from the outside. This flattens the stitches and makes the hem invisible from the front.
Sew a curved hem by hand
Hand-sewing is better for tight curves — armholes, necklines, and the openings of fitted sleeves — because you can feel exactly how much tension the fabric needs. Use a needle that fits comfortably in your hand and thread that matches the garment. A size 8 or 9 needle works for most fabrics.
Start at a seam or a point where the curve changes direction. Bring the needle up through the fold of the hem from the inside, then take a tiny stitch (about 1/16 inch) into the garment body just above the fold. Bring the needle back down into the fold and slide it along inside the fold for about 1/4 inch, then come back up and take another tiny stitch. This is called a slip stitch, and it is nearly invisible from the outside because the thread runs inside the fold.
Keep your stitches small and even, and maintain gentle tension — the thread should be snug enough to hold the hem in place but not so tight that it puckers the fabric. Work your way around the curve, checking the outside of the garment as you go to make sure the hem is lying flat. Once you reach the starting point, tie off the thread with a small knot inside the fold.
Fix puckering or bunching after sewing
If the hem puckers after you sew, the most common cause is uneven easing — you stretched too much in some places and not enough in others. The fix depends on how bad it is. If the puckers are small and only in one or two spots, you can often press them out with a hot iron and steam. Lay the garment flat, spray the puckered area with water, and press with a hot iron until the fabric relaxes.
If the puckers are deep or cover a large area, you may need to remove the stitches and resew. Use a seam ripper to cut the thread every few stitches, then pull the thread out. Unpin the hem, repin with more careful easing, and sew again. This is tedious, but it is faster than living with a bumpy hem.
If the hem bunches on the inside (the allowance folds up instead of lying flat), the curve was too tight for the hem allowance you used. Trim the allowance even narrower and add more clips if needed, then repin and resew.
Curved hems on different garment pieces
The technique changes slightly depending on where the curve is. On a circular skirt hem, the curve is gentle and the hem allowance can be wider (1/2 to 3/4 inch). You can use a machine and sew quickly. On an armhole or neckline, the curve is tight and the allowance must be narrow (1/4 inch). Hand-sewing is usually easier because you can control the tension precisely. On fitted sleeves, the curve is moderate and you can use either method, but a machine is faster if the curve is not too sharp.
For bias-cut garments — pieces cut at a 45-degree angle to the grain of the fabric — the fabric is naturally stretchy and curves easily. You can use a wider hem allowance and sew by machine without much easing. For knit fabrics, use a ballpoint needle and a slight stretch stitch (if your machine has one) instead of a straight stitch, because knits need a little give so the hem does not snap when you wear the garment.
Frequently Asked Questions
Can I use a serger to sew a curved hem?
Yes, but only on gentle curves. A serger trims and finishes the edge at the same time, which is fast on a straight hem or a slight curve. On a tight curve, the serger can stretch the fabric unevenly and create puckers. If you want to use a serger, test it on a scrap of the same fabric first.
What if the curve is so tight I cannot fold the hem at all?
You may need to use a facing instead of a hem. A facing is a separate piece of fabric sewn to the edge and folded to the inside, and it works better than a hem on very tight curves like a deep neckline. Consult a sewing pattern or book for facing instructions, as the method varies by garment type.
Do I have to clip the hem allowance on every curved hem?
No. Clipping helps on tight curves, but on gentle curves like a circular skirt it is not necessary. If you clip and the notches create a wavy edge, you clipped too much. Start with no clips, and only add them if you see bunching after you pin.
How do I keep the hem from rolling after I wash the garment?
Press it flat after every wash while it is still damp. A curved hem that rolls usually means the stitches are too loose or the easing was uneven. If rolling is a persistent problem, you can topstitch the hem — sew a second line of stitches about 1/4 inch away from the first — which holds it in place permanently.