Piecing Efficiency Calculator — Fabric Waste from Cutting
Enter your piece type and size, the number of pieces, and your fabric width. The calculator lays the pieces out across the width of fabric (WOF), counts the rows, and compares the practical fabric area you actually cut to the theoretical area of the pieces themselves — the difference is your geometric cutting waste. Triangles are cut from squares (2 per square). The cutting method informs scrap-utilization tips only; the waste percentage is the geometric layout waste, which is verifiable from the cutting layout.
What this calculator determines
It calculates the theoretical versus practical fabric area and the geometric cutting waste when cutting squares, rectangles, triangles, or strips from width-of-fabric.
Related calculators
Fabric Yardage Calculator
Yardage needed to cut a quantity of same-size pieces from fabric of any width
Quilt Block Layout Calculator
How many blocks fit and how to arrange them, with sashing and borders
Quilt Block Size Calculator
Cut size for a finished block — finished size plus two seam allowances
Sashing Calculator
Sashing fabric yardage from block layout, sashing width, and fabric width
Quilt Border Calculator
Border fabric yardage for straight borders, single or multiple
Examples
100 squares, 2.5″, 42″ WOF → 0.5 yd (15.0% of purchase wasted)
100 squares, 2.5″, 42″ WOF, rotary
Calculation
- 16 across (42 ÷ 2.5 = 16.8 → 16)
- 7 rows (100 ÷ 16 = 6.25 → 7)
- Linear 17.5″ → 17.5 ÷ 36 = 0.4861 yd → buy 0.5 yd
- Practical 735 sq in vs theoretical 625 sq in → waste 110 sq in
- Waste = 15.0% of purchased area; 17.6% overhead on piece area
0.5 yd — 15.0% of purchased fabric wasted (17.6% overhead on piece area)
50 rectangles, 3″×6″, 42″ WOF → 0.75 yd (10.7% of purchase wasted)
50 rectangles, 3″×6″, 42″ WOF, rotary
Calculation
- 14 across (42 ÷ 3 = 14)
- 4 rows (50 ÷ 14 = 3.57 → 4)
- Linear 24″ → 24 ÷ 36 = 0.6667 yd → buy 0.75 yd
- Practical 1008 sq in vs theoretical 900 sq in → waste 108 sq in
- Waste = 10.7% of purchased area; 12.0% overhead on piece area
0.75 yd — 10.7% of purchased fabric wasted (12.0% overhead on piece area)
Assumptions & Conventions
- WOF layout
- Pieces are laid out across the usable fabric width in whole numbers; the leftover width per row is geometric waste.
- Triangles from squares
- Half-square triangles are cut from squares (2 per square), so the layout counts squares, not triangles.
- Purchase rounding
- Yardage is the linear length (rows × piece length ÷ 36) rounded up to the next 1/8 yard, never area ÷ 1296.