Gathering & Ruffle Fabric Calculator

How it works

Strip length = finished edge × fullness ratio; cut width = depth + hem + seam allowance; crosswise strips = ⌈(strip length + joins) ÷ usable width⌉; fabric = strips × cut width

Gathering compresses a long strip onto a shorter edge, and the ratio between them — the fullness — sets the look: 1.5× is gentle and suits heavy fabric, 2× is the workhorse, 3× and more for sheers and tulle, which collapse without it. The strip is almost always pieced from crosswise cuts of the fabric width, so the number of strips (and joins) comes from dividing the total length by the usable width, and the fabric needed is simply strips times cut width — which is why a deep ruffle in a narrow fabric eats yardage fast. The cut width adds hem and seam allowances; a folded double ruffle avoids hemming at the cost of twice the depth. Dividing both the ruffle and the edge into equal marked sections before drawing up the gathers keeps the fullness even.

Worked example

A 15 cm ruffle at 2× fullness on a 180 cm edge needs a 360 cm strip cut 18 cm wide. In 112 cm fabric that is four crosswise strips (three joins) — 72 cm of fabric, buy 75 cm. For a tiered skirt the next tier would be 720 cm.

Frequently asked questions