A machine blind hem is sewn with the blind-hem stitch, a few straight stitches followed by one wide zigzag that swings to the left, and a blind-hem foot with a guide blade. Press the hem allowance up, then fold the hem back under the garment so that about 6 mm (1/4 in) of the finished hem edge sticks out past the fold, and sew along that edge with the guide against the fold: the straight stitches land on the hem allowance and each zigzag catches one or two threads of the garment fold. Unfold and press, and only tiny dots show on the outside.

What is a machine blind hem and when does it work?

A blind hem hides its stitching on the outside of the garment. By hand it is done with a catch stitch or slip stitch; by machine, the blind-hem stitch does the same job in a fraction of the time. The result is nearly invisible on textured, medium and heavy fabrics (wool, tweed, denim, twill, crepe, ponte) and on anything with a print, which is why it is the hem of choice for trousers, straight skirts, jackets and curtains.

On smooth, light, plain fabrics such as poplin or satin, each stitch pulls a small dimple, and a hand hem or a narrow topstitched hem looks better. The comparison of hand and machine hems helps you decide.

What do you need to sew a blind hem?

  • The blind-hem stitch on your machine. It looks like a row of dashes with a V every few stitches. Many machines have two: one with straight stitches between the zigzags, for wovens, and a stretch version with tiny zigzags between them, for knits.
  • A blind-hem foot, with an adjustable or fixed metal blade that rides along the fold. Most machines include one. Without it, you can use a standard foot and the needle position, but the foot makes the result consistent.
  • A hem allowance of 3–4 cm (1 1/4–1 1/2 in) on trousers and skirts, 5 cm (2 in) on jackets and curtains. The deeper the hem, the better it hangs.
  • Thread matching the fabric exactly, because the dots that do show are the thread. On a fabric between two colors, choose the darker one.
  • An iron and a tailor's ham for curved hems, plus a seam gauge.

How do you fold the fabric for a blind hem?

This fold is the whole technique, and it is the part people find confusing, so follow it on a scrap first.

  1. Finish the raw edge of the hem allowance with a zigzag, a serger or pinking. On a light fabric you can fold the edge under 6 mm (1/4 in) instead.
  2. Press the hem allowance up to the wrong side at the hem depth, say 3.5 cm (1 3/8 in), and pin it.
  3. Now fold the garment back on itself, right sides together, along a line 6 mm (1/4 in) inside the finished edge of the hem allowance. The hem allowance's finished edge should stick out 6 mm past this new fold. What you see is: a narrow strip of hem allowance on top, then the fold, then the body of the garment underneath.
  4. Press this second fold lightly, or pin it every 8 cm (3 in) with the pin heads toward you.

Seen in cross-section, the fabric makes a Z: the garment, the fold, and the hem allowance going back the other way with its edge protruding.

How do you sew a blind hem step by step?

  1. Select the blind-hem stitch, width 2–3 mm, length 2.5–3 mm. Fit the blind-hem foot.
  2. Place the fabric under the foot wrong side up, with the protruding 6 mm strip of hem allowance to the right of the foot's blade and the fold pressed against the left side of the blade.
  3. Check where the zigzag lands. Turn the handwheel by hand through one full pattern. The straight stitches should sit on the hem allowance strip, 2–3 mm from its edge, and the single zigzag should swing left and bite the fold by one or two threads. If it bites too deep, move the blade a little to the right or narrow the stitch; if it misses, move it left or widen the stitch.
  4. Sew the whole hem at a moderate speed, keeping the fold against the blade the entire time. The blade does the guiding; your hands keep the fold even.
  5. Overlap the start by 2 cm (3/4 in) and remove the pins.
  6. Unfold the hem and press it flat from the wrong side, then from the right side with a pressing cloth. Pull the hem open gently with your fingers first if it wants to stay folded.

The stitches on the outside are the tips of the zigzags: dots 1 cm apart or so, the length of one stitch pattern. On tweed they disappear; on a plain twill they are visible from close up and invisible from a meter away.

How do you adjust the blind hem so it does not show?

The visibility of the hem depends on how much fabric each zigzag catches. One thread is ideal, two is fine, four is a visible dimple. Three things control it:

  • Blade position: the blade sets the distance between the fold and the needle. Moving it right by 0.5 mm makes a big difference.
  • Stitch width: narrower zigzags bite less. 2 mm is enough on most fabrics.
  • The fold itself: a fold that is pressed hard and runs straight lets the needle skim it; a soft or wavy fold gets caught by too much.

Test on a scrap of the same fabric folded the same way, and look at the right side before you touch the garment. A seam ripper undoes a blind hem quickly, but it leaves needle holes in satin and some synthetics.

Can you blind hem knit fabric by machine?

Yes, with the stretch blind-hem stitch, which replaces the straight stitches with small zigzags so the hem can stretch. Use a ballpoint or stretch needle, a slightly longer stitch of 3 mm, and do not finish the edge of the allowance: knits do not fray and a serged edge adds bulk that shows. Keep the hem relaxed as it feeds. On very stretchy fabrics the hem will still be less elastic than a twin-needle hem, so the comparison of twin needle, coverstitch and zigzag hems is worth reading before you choose. If you are sewing knits for the first time, the knit fabric guide covers the rest of the setup.

Common mistakes with machine blind hems

  • The zigzag misses the fold completely. The fold drifted away from the blade. Keep gentle pressure to the right so the fold stays in contact.
  • Big dimples on the outside. The zigzag bites too deep. Narrow the width, move the blade right, or both.
  • The hem allowance edge shows below the stitches. The protruding strip was wider than 6 mm, so the straight stitches landed too far from the edge. Keep it at 6 mm.
  • A wavy hem on a curve. The hem allowance was longer than the garment where it is pressed, as on a flared skirt. Reduce the allowance to 2 cm (3/4 in) on flared hems, or ease the edge with a line of gathering stitches before pressing.
  • Thread color off by a shade. It is the one thing that cannot be fixed afterward. Match it in daylight.

Sewly's pull-on trousers and pencil skirt come with a 3 cm (1 1/4 in) hem allowance in the pattern, and the sewing guide tells you at which step to hem; the blind hem is a good choice for both.

When should you use a blind hem instead of a topstitched hem?

Choose a machine blind hem on trousers, tailored skirts, jackets and curtains in medium and heavy fabric, wherever a visible row of stitching would look casual. Choose a topstitched double-fold hem on jeans, shirts, casual dresses and anything where the stitching is part of the look, and on light, smooth fabrics where the blind hem dimples. For sheers and curved hems, a rolled hem is lighter: see how to sew a rolled hem. And for the softest finish on a special garment, the hand hem in the hemming guide remains the most invisible of all.