How quilt fabric calculator Works
Backing: the geometry of wide fabric
Standard quilting cotton runs 42–44 inches wide, so almost every backing needs seamed panels. The classic recipe: add 8 inches of overage to each quilt dimension, cut panels of that length, and seam them until they match the width. The calculator computes panel count and converts to yardage. The pro shortcut: 108-inch wide backing fabric needs one uncut piece — the calculator handles that option too, and for queen-plus quilts the price difference usually favors it.
Seam the panels properly
- Remove the selvedges before seaming — they don't shrink with the fabric and make a hard ridge.
- Use a ½-inch seam and press it open for a flat back.
- Stagger odd panel counts — three-panel backs look better with the seams off-center.
Binding: perimeter math
Binding length = perimeter + 10 inches for corners and joining (the calculator adds 10%). Divide by a 40-inch usable strip to get strip count, then multiply strips × strip width for yardage. Cut strips on the straight grain for durability; bias binding is for curved edges only — it consumes fabric and stretches out of shape on straight quilt sides.