A few useful things to know
How to use this fabric calculator
A quilt pattern changes the cutting maths. This tool supports three explicitly defined layouts: whole squares, four-patch blocks and nine-patch blocks. It counts the pieces, packs equal squares into cross-width strips and adds your chosen cutting reserve.
- Choose the finished quilt size you want to cover. Whole blocks round the quilt up to that size; the result shows the actual finished dimensions.
- Select a supported block and its finished size. Four-patch blocks contain four equal squares; nine-patch blocks contain nine.
- Choose one fabric or the displayed two-fabric layout. Nine-patch blocks use fabric A at the corners and centre, with B at the four remaining positions.
- Check the strip and square counts for each fabric. Backing, binding, borders and sashing are separate.
A worked example
A 60 × 72 inch quilt of 12-inch four-patch blocks uses 5 columns × 6 rows = 30 blocks. With ¼ inch seams, cut 6½-inch squares: 60 each in fabrics A and B. Six fit across 42-inch fabric, so cut ten strips per fabric. The exact strip plan uses 65 inches per fabric. A 10% reserve gives 71½ inches; round each purchase to 2 yards.
The method behind the result
Columns = ceil(target width / finished block size); rows = ceil(target length / finished block size). A block has 1, 4 or 9 squares. Cut square size = finished block size / squares along one side + 2s. Squares per strip = floor(usable fabric width / cut square size). For each fabric, strips = ceil(piece count / squares per strip).
What this plan assumes
Exact piece counts apply to the displayed square-based layout only. Yardage is an estimate for strip cutting, with a separate percentage reserve. There is no sashing, border, appliqué, half-square triangle, on-point setting or stripe matching. Fabric A/B are pooled yardage, not estimates for individual prints in a scrappy quilt.
Common mistakes to avoid
- Expecting one area formula to cover every quilt pattern.
- Forgetting seams between the small squares within a block.
- Dividing total yardage equally among prints without counting their pieces.
- Treating a target size as exact when it needs a partial row of blocks.