Quilt Backing and Binding Calculator (Fabric Needed)

What this tool does

Backing has to be larger than the top, usually by several inches all round, and quilting cotton is only about 40–42 in (100–107 cm) wide once the selvedges are cut off, so a quilt wider than that needs two or three pieces seamed together. The calculator tries the seams running both ways and gives the shorter length of fabric to buy. Binding is the perimeter plus 10 to 12 in (25–30 cm) for the corners and the joins between strips; strips are cut across the fabric width, commonly 2¼–2½ in (6–6.5 cm) wide. Use one unit for every figure — inches or centimetres — and the answers come out in that unit; the defaults are in inches.

Formula

backing = pieces × (length + margin), pieces = ⌈(width + margin) ÷ fabric width⌉, turned whichever way needs less · binding = perimeter + extra, strips = ⌈binding ÷ fabric width⌉

Variables

Worked example

Limitations

• Mixing units is the most common source of error. Convert every input to the units shown next to each field before calculating.
• Always order a little more material than the calculated quantity. Cuts, breakage and pattern matching create waste that depends on the shape of the job.