Quilt Size Calculator

How it works

width = blocks across × block + sashing strips across × sashing + 2 × border · length = blocks down × block + sashing strips down × sashing + 2 × border · sashing strips = blocks − 1 (or blocks + 1 with outer sashing) · binding = perimeter + 25 cm (10 in) for joins and corners

Quilt maths always uses finished sizes — what you see after sewing — and seam allowances are added only when you cut. Between the blocks the sashing adds one strip fewer than the number of blocks (or one more if it also frames the outside), and the borders add their width on both sides. The closest standard size is a guide based on common mattress-top quilt sizes (crib 36 × 52 in, throw 50 × 65, twin 70 × 90, full 85 × 108, queen 90 × 108, king 108 × 108); for a bedspread that drapes to the floor add the mattress depth on three sides.

Worked example

Thirty 30 cm blocks set 5 across and 6 down with 5 cm sashing between them and a 10 cm border: 5 × 30 + 4 × 5 + 2 × 10 = 190 cm wide and 6 × 30 + 5 × 5 + 2 × 10 = 225 cm long — a 190 × 225 cm quilt, closest to a twin (178 × 229 cm). It needs 24 short sashing pieces, 5 long strips of 170 cm and about 855 cm of binding.

Sources: Wikipedia — Quilt · Wikipedia — Bed size

Frequently asked questions