Fabric Yardage Calculator
How many yards of fabric to buy for any number of pieces, from the piece size and the bolt width, rounded to the 1/8 yard.
How this is calculated
Pieces are laid out in rows across the width of the fabric: the number that fit across is the fabric width divided by the piece width, rounded down. The rows needed are the number of pieces divided by that, rounded up, and the length of fabric is the rows times the piece length. Both ways of turning the piece are tried, and the shorter length is used.
A yard is 36 inches. US fabric stores cut by the 1/8 yard (4.5 inches), so the length is rounded up to the next 1/8 yard. If you plan to prewash, add the shrinkage percentage you expect for the fabric; it is added to the length.
Measure pieces with the seam allowance included. The selvages (the woven edges) are usually trimmed off, so if your pieces fit the width exactly, choose the next smaller number or allow an extra inch.
Limits
Pieces of one size, and fabric without a one-way print or nap (which stops pieces being turned). For a pattern with many different pieces, use the pattern's own yardage chart.