Knife pleats, box pleats and inverted pleats are the same fold arranged three ways. A knife pleat is one fold pressed to one side, and a row of them all face the same way. A box pleat is two knife pleats folded away from each other so a flat panel sits between them on the right side; an inverted pleat is the same pair folded toward each other, so the folds meet on the right side and the box is on the inside. Each pleat takes three times its visible width in fabric, and all three are sewn the same way: mark the fold and placement lines, fold, press, baste across the top and stitch them into the seam.
| Knife pleat | Box pleat | Inverted pleat | |
|---|---|---|---|
| Folds | One, all facing the same way | Two, facing away from each other | Two, facing toward each other |
| Right side shows | A row of overlapping folds | A flat panel between two folds | Two folds meeting at a line |
| Fabric needed | 3 times the finished width | 3 times the finished width | 3 times the finished width |
| Typical use | Kilts, school skirts, sleeve heads | Skirts, shirt backs, pocket fronts | Skirt center front, shirt back, kick pleats |
| Best fabric | Crisp wool, cotton, poplin | Medium-weight cotton, twill, wool | Any, including soft fabrics |
How much fabric does a pleat take?
A pleat has three layers across its width: the visible face, the fold underneath and the fabric that returns to the surface. So a 4 cm (1 5/8 in) knife pleat uses 12 cm (4 3/4 in) of fabric, and a skirt with twelve such pleats around a 72 cm (28 1/4 in) waist needs 72 plus 96 cm, or 168 cm (66 in) of fabric at the waist. A box pleat with a 6 cm (2 3/8 in) face and two 3 cm (1 1/4 in) folds beneath uses 12 cm too: the face plus two folds each twice their depth.
Pleats can also be shallower than full, with the underfold less than the face. A knife pleat with a 4 cm face and a 2 cm underfold uses 8 cm and the pleats no longer overlap.
What do you need?
- A crisp or medium-weight fabric that takes a press: cotton poplin, twill, linen, wool suiting. Pleats in viscose or jersey fall out unless stitched down.
- Tailor's chalk or an erasable marker, a ruler and a pattern with pleat lines, or a strip of card cut to the pleat width as a template.
- Pins or clips, a pressing cloth, and a tailor's clapper or a wooden ruler to flatten the folds after steaming.
- Optional: a strip of fusible interfacing for the waist seam of a pleated skirt.
How do you mark pleats?
Every pleat has two lines: a fold line, where the fabric creases, and a placement line, where the fold lands. On a pattern the fold line is usually solid and the placement line dashed, with an arrow showing which way the fold goes. Mark both on the wrong side with chalk, and snip 3 mm (1/8 in) into the seam allowance at the top of each line so you can see them from the right side. Transferring pattern markings covers the thread tacks that last through the pressing.
For a skirt without a pattern, mark on a long rectangle: for 4 cm knife pleats, mark a fold line, then a placement line 8 cm (3 1/8 in) further on, then the next fold line 4 cm after that, and repeat. A card template with the two distances marked is faster than measuring each one.
How do you sew knife pleats?
- Fold on the first fold line, wrong sides together, so the crease is on the right side. Bring the crease over to the placement line and pin it in place through all three layers.
- Repeat for every pleat, all folding the same way. Check from the right side that the pleats are even by measuring the face of each; a difference of 2 mm shows across a skirt.
- Baste across the top at 1 cm (3/8 in) from the raw edge, inside the seam allowance, with a regular stitch. The pleats are now held for the rest of the construction.
- Press. Lay the pleats face down on the board, cover with a pressing cloth, steam without sliding the iron, then press the clapper down on the folds while they cool. Press from the top to the hem. How to press seams properly explains why the clapper matters on wool.
- Hem before the final press if the hem crosses the pleats, then re-press the lower folds through the hem.
- Secure the top edge by sewing the waistband or yoke across the basted pleats. If you want the pleats to hang open from the hip rather than the waist, stitch each fold line down from the waist for 10 to 15 cm (4 to 6 in) first, and press the stitched part flat.
How do you sew box pleats?
- Mark a center placement line, and a fold line on each side of it. For a 6 cm face with 3 cm underfolds, the fold lines are 3 cm either side of the center and the placement line is the center line itself.
- Fold on the right fold line and bring the crease to the center line; fold on the left fold line and bring its crease to the center line. The two creases meet at the center on the wrong side, leaving a flat 6 cm panel between two outward folds on the right side.
- Pin and baste across the top as for knife pleats.
- Press the folds, then open the pleat from the wrong side and press the two underfolds flat against the garment so the pleat lies evenly.
- Edgestitch the folds 2 mm (1/16 in) from each crease for a tailored look, from the top down, stopping where the pleat should open. On a shirt back, a single box pleat below the yoke is stitched only in the yoke seam.
How do you sew inverted pleats?
An inverted pleat is a box pleat turned over, and it is the easiest of the three to sew because it can be stitched on a seam.
- With a seam: sew the seam, for example the center front of a skirt, from the waist down to where the pleat should open, with a regular stitch. Continue to the hem with a long basting stitch.
- Press the seam open, then open out the seam allowances and center the fabric under the seam line so both halves of the underlay are equal. Pin the pleat in place from the right side.
- Baste across the top, then topstitch from the right side 1 cm either side of the seam line to the point where the pleat opens, finishing with a short horizontal bar across the base if the pleat is a kick pleat on a pencil skirt.
- Remove the basting in the seam below the opening and press the folds.
Without a seam, mark two fold lines and a center placement line, fold each crease toward the center line on the right side, and proceed as for a box pleat.
What are the most common mistakes with pleats?
- Uneven pleats. Measure every face after pinning, before the first press. A card template beats a ruler for speed and consistency.
- Pressing with a sliding iron. The layers shift and the folds end up curved. Lift and lower the iron, then use the clapper.
- Shine on the right side. Wool and dark cotton shine under direct pressing. Always use a pressing cloth, and press from the wrong side when possible.
- Skipping the top basting. The pleats shift while the waistband goes on and the waist ends up a different size from the pattern.
- Cutting the hem allowance short. A hem across pleats needs re-pressing; allow 3 cm (1 1/4 in) so the folds through the hem are crisp.
When should you use pleats instead of gathers or darts?
Pleats give fullness in flat, controlled folds, so they suit crisp fabric and a tailored look; gathering gives soft, random fullness and suits light and drapey fabric. For a skirt, a pleated version uses more fabric than a gathered one of the same fullness but lies flatter at the waist. A single inverted or box pleat is also a way to add walking room to a straight skirt without the volume of flare: the pencil skirt with a back vent and the A-line skirt in Sewly are the natural starting points, since the pleat is added to a rectangular extension of the center seam.