A bias-cut slip dress is a front and a back cut at 45° to the grain, joined at the sides with French seams, finished along the top with bias binding and hung from thin spaghetti straps, then left to hang for a day and hemmed narrow. It has no zip and no darts: cut on the bias, a woven fabric gives enough to pull on over the head and drapes over the body. The sewing itself is short; the care goes into cutting and handling a slippery fabric.

The pattern pieces for size EU 38 / US 6, drawn by Sewly's drafting engine (seam allowances included). Slip dress →

Why is a slip dress cut on the bias?

Woven fabric barely stretches along its lengthwise or crosswise threads, but it gives noticeably along the bias, the diagonal at 45°. Cut that way, the dress molds over the bust and hips, falls in soft folds, and slips on without an opening. The price is more fabric, a hem that grows as the dress hangs, and seams that ripple if you stretch them while sewing.

Which fabric, and how much?

Choose a fabric that drapes: polyester satin (the easiest satin to sew), silk charmeuse, viscose crepe, cupro or sandwashed silk. Stiff satins such as duchesse do not drape on the bias and look like a tube. For a first slip dress, viscose crepe or cupro is less slippery than charmeuse and more forgiving.

Bias pieces sit diagonally on the fabric, so they use much more of it than straight-grain pieces. For a midi on 140 cm (55 in) fabric, plan roughly 2.5–3 m (2 3/4–3 1/4 yd) depending on your size, and more for a maxi. The binding and straps come out of the leftover triangles.

How do you cut fabric on the bias accurately?

  1. Prewash washable fabrics, since viscose can shrink, and press them flat.
  2. Make full pattern pieces. If the pieces are drawn on a fold, trace each one, flip the tracing along the center line and tape the halves together. Folding slippery fabric on the bias tends to twist the layers, so cut everything in a single layer.
  3. Align the grainline at exactly 45° to the selvage: measure from the selvage to each end of the grain arrow, and adjust until both distances are equal.
  4. Stabilize. Lay tissue paper or thin pattern paper under the fabric and cut through both. Use pattern weights instead of pins, and a rotary cutter if you have one.
  5. Mark the notches with short snips or tailor's tacks; chalk does not always show on satin.

How do you sew a bias-cut slip dress, step by step?

  1. Handle the pieces flat. Do not hang them or let them dangle off the table while you work.
  2. Side seams as French seams. Sew the sides wrong sides together 6 mm (1/4 in) from the edge, trim to 3 mm (1/8 in), press, fold right sides together and sew again 9 mm (3/8 in) from the fold. The two passes use up the 1.5 cm (5/8 in) allowance and enclose the raw edges; see French seams.
  3. Straps. Sew two bias tubes, 6 mm (1/4 in) wide finished and 48 cm (19 in) long, and turn them with a loop turner.
  4. Fit the straps. Pin them to the front at the top points, try the dress on, and pin them to the back at the length that sits right.
  5. Bind the top edge. Cut a bias strip 3.5 cm (1 3/8 in) wide, long enough for the whole top edge and the armholes. Bind the front, armholes and back in one pass, catching the strap ends under the binding. The bias binding guide shows the technique.
  6. Hang the dress for 24 hours, or 48 for viscose, on a padded hanger or a dress form.
  7. Level the hem by measuring up from the floor while the dress is worn, then sew a narrow hem on the 1 cm (3/8 in) allowance.
  8. Press with a pressing cloth, at a low temperature for silk and synthetics.

Use a microtex needle 60/8, fine thread and a stitch length of about 2 mm. A strip of tissue paper under each seam stops the feed dogs from chewing the fabric; tear it away afterward.

How do you stop slippery fabric from moving?

  • Cut and sew on a large table, with the whole piece supported.
  • Hand-baste the side seams before machine sewing them.
  • On washable fabrics, a light spray starch firms the fabric for cutting and washes out later.
  • Let the fabric feed by itself. Pulling it stretches the bias, and the seam ripples once the dress hangs.

How should a slip dress fit?

A slip dress skims rather than grips. The body has about 10 cm (4 in) of ease at the bust, no darts, and a flare from the hip of 6 cm (2 3/8 in) at each side seam by default. The bias accommodates a moderate bust; with a fuller bust, test the fit in an inexpensive drapey fabric first. Neckline options are a straight top, a V that dips 3.5 cm (1 3/8 in) at the center, or a deeper soft cowl.

Sewly's slip dress pattern marks the bias grainline on each piece, sizes the binding and straps for you, and lists the needle and tissue paper among the notions. If your satin keeps sliding at a particular step, you can ask the guide about that step and get an answer for your own pattern.