Drafting Pleats: Knife, Box and Inverted

Every pleat has three lines: the fold line where the fabric turns to the outside, the placement line where the fold is brought to lie, and the underlay hidden behind. The distance between fold and placement is the pleat depth, and behind every visible pleat sits twice that depth in folded fabric. This is why pleated garments feel substantial and use so much cloth.

Pleats are marked on the pattern with these lines clearly distinguished, usually a solid line for the fold and a broken line for the placement, plus arrows showing the direction the fold travels. Reading them correctly is essential, because a pleat folded the wrong way ruins the panel.

A knife pleat is the simplest: all folds face the same direction, each fold laid over the next like tiles. It gives a clean, uniform, directional look, classic on school skirts and pleated skirts. To draft a run of knife pleats, decide the finished pleat width, then add twice that width behind each one for the underlay.

For a fully pleated panel where the pleats touch, the flat fabric width is three times the finished width, because each visible pleat width conceals two hidden layers. If the pleats are spaced apart, the ratio is lower and you calculate the underlay per pleat and add it to the flat sections between them.

• A box pleat is two knife pleats facing away from each other, folding outward to leave a flat panel on the face.
• An inverted pleat is the reverse, two knife pleats facing toward each other and meeting at the center.
• Both consume the same underlay: twice the pleat depth on each side of the pleat.
• The inverted pleat is common at center front or center back for walking ease.
• A row of box pleats and a row of inverted pleats are the front and back of the same fold, viewed from opposite sides.

1. 1.Decide the finished visible width of each pleat.
2. 2.Multiply the pleat depth by two to find the fabric hidden behind each fold.
3. 3.Add that hidden amount to the visible width for the total fabric per pleat.
4. 4.Multiply by the number of pleats across the panel.
5. 5.Add any flat, unpleated sections and seam allowances to reach the total flat width.

Pleats must be marked precisely on the pattern and transferred accurately to the fabric, because a run of pleats that drifts even a millimetre per pleat becomes visibly uneven across a panel. Use notches at the top and drill holes or tailor's tacks to mark fold and placement lines, and keep the pleats on grain so they hang straight.

Pleats are held by pressing, by a stitched section at the top, or by edgestitching the fold its whole length for a permanent crisp line. Fabric matters: crisp wools and firm synthetics hold a pleat, while soft drapey cloth needs topstitching or will fall out of pleat with wear.

Pleated panels carry dense line information, fold lines, placement lines and direction arrows, that must survive digitizing without ambiguity. Minerva Patterns supplies pleated skirts and dresses as DXF AAMA, PLT and PDF, with every fold and placement line and the pleat direction clearly marked, so a full run of pleats reproduces evenly on the cutting table.

Whichever type you choose, the discipline is the same: fix the finished width, account for twice the depth behind every fold, and mark the lines so precisely that the pleats stay even across the whole panel.