It is built for simple patchwork made of one square size: a classic squares quilt, a charm-style scrappy top, or the background squares of a larger design. For borders, backing and binding, use the matching calculators linked below, then add the totals together for a full shopping list.
Worked example: a throw quilt of 5 inch squares
A 50 x 65 in throw made of 5 in finished squares.
- Squares across: 50 / 5 = 10. Squares down: 65 / 5 = 13. Total: 10 x 13 = 130 squares.
- Cut size: 5 + 1/2 = 5 1/2 in, to include a 1/4 in seam allowance on every side.
- Squares per strip: 42 / 5 1/2 = 7 (rounded down).
- Strips: 130 / 7 = 19 (rounded up), each 5 1/2 in deep, so 104 1/2 in of fabric.
- 104 1/2 in / 36 rounds up to 3 yd.
- Spread across four fabrics instead, each needs 33 squares, 5 strips and 7/8 yd, or 3 1/2 yd in all. Partial strips are why several fabrics need more in total than one.
Result: 3 yd of one fabric, or 7/8 yd each of four fabrics.
How the yardage is calculated
- Squares across = quilt width / finished square size, rounded up. Squares down = quilt length / finished square size, rounded up. If your square size does not divide the quilt evenly, the top finishes slightly larger, and the calculator shows the real finished size.
- Cut size = finished size + 1/2 in (a 1/4 in seam allowance on each side).
- Squares per strip = usable fabric width / cut size, rounded down. The default usable width is 42 in, which is typical quilting cotton after the selvages are trimmed.
- Strips = squares for that fabric / squares per strip, rounded up. Fabric length = strips x cut size.
- Yards = fabric length / 36, rounded up to the next 1/8 yard (4 1/2 in), the smallest cut most quilt shops sell.
Assumptions
- Usable width of fabric is 42 in unless you change it. Measure yours: some fabrics give 40 in, some 44 in.
- Seam allowance is 1/4 in, so each square is cut 1/2 in larger than it finishes.
- No allowance for shrinkage, straightening the fabric or cutting mistakes. Many quilters add 1/8 to 1/4 yard per fabric as a margin.
- Squares are split as evenly as possible between fabrics; each fabric is rounded up on its own.
Frequently asked questions
How much fabric do I need for a throw quilt?
It depends on the design. For a 50 x 65 in throw made of 5 in finished squares, the top needs 3 yd of one fabric, or 7/8 yd each of four fabrics. Backing, binding and borders are extra.
Why does splitting squares across more fabrics need more yardage?
Each fabric is cut in whole strips. When a fabric needs only part of its last strip, the rest of that strip is left over, and that leftover repeats for every fabric. The calculator rounds each fabric up separately so you never come up short.
What width of fabric does the calculator assume?
42 in usable width, which is common for quilting cotton sold as 42 to 44 in wide once the selvages are trimmed away. Enter your own measurement if your fabric is narrower or wider.
Does this include backing, binding or borders?
No. This calculator covers the pieced squares only. Use the backing, binding and batting calculators for the rest of the quilt, and add each border as its own strips.
Should I buy extra fabric?
The result is the minimum for clean cutting. Pre-washing can shrink cotton, and a crooked cut or a mis-cut square eats into the margin, so many quilters round up by 1/8 to 1/4 yard per fabric.