Cushion Cover Calculator
Calculate cut sizes for a simple rectangular envelope cushion cover: one front piece and two equal overlapping back pieces.
Construction assumed: one front rectangle and two equal back rectangles that overlap at the centre. The opening edge of each back panel is hemmed; the other three edges are caught in the outer seam.
Front cut width = finished width + 2 × seam allowance. Front cut height = finished height + 2 × seam allowance. Each back panel uses the same cut width. Its cut height = (finished height + total overlap) ÷ 2 + one outer seam allowance + the opening hem allowance.
Before cutting
Check whether you want a snug finished cover, especially for a soft insert. Directional prints, pattern matching, piping and zipper construction can change the pieces you need.
Worked example
For a finished 45 × 45 cm cushion, a 1 cm seam allowance gives a 47 × 47 cm front. With 12 cm total overlap and a 3 cm opening hem allowance, each equal back panel is cut 47 × 32.5 cm.
Common question
Can I use this for a zippered cover? Not directly. A zipper changes the back construction and seam sequence; this tool is specifically for an envelope opening.
Related sewing tools
Seam Allowance Calculator · Fabric Yardage Calculator · Fabric Shrinkage Calculator