Fabric Yardage for Quilts

Ten percent is a common quilting rule of thumb that covers routine risks — a mis-cut piece, shrinkage from pre-washing cotton, or a small flaw in the fabric that forces you to cut around it — without dramatically over-buying. If you're working with a directional print, a fabric prone to fraying, or a pattern that needs careful color matching across pieces, many quilters increase that cushion beyond 10%.

Fabric is sold by length, and if the math rounded down even slightly, you'd arrive at the register short of what your cutting layout actually requires. Rounding up to the next hundredth of a yard guarantees the purchased length always covers every row of pieces, even when the exact requirement falls just short of a clean fraction.

A larger seam allowance is added to both sides of each piece's width and height before the layout is calculated, so it makes every individual cut piece bigger — which can reduce how many pieces fit in a single row across the fabric width and push some pieces into an additional row. In practice this means a larger seam allowance often increases total yardage more than its small size suggests, especially when it pushes your layout past a row boundary.

No — it only measures the unused space in the final, partially filled row of your layout, comparing how many piece slots that row could hold against how many pieces you actually still need. It does not account for narrow leftover strips between rows, fabric lost to matching a directional print, or trimming irregular selvage edges, so actual scrap on the cutting table is often higher than this figure suggests.