Fabric Yardage from Pattern Pieces
Fabric length for a list of pattern pieces with seam allowance, laid in rows across your fabric width; repeat, shrinkage and extra are inputs, not assumptions.
Yards or metres to buy for the pieces you list, the row-by-row layout that explains the number, the unused share, and what a pattern repeat, pre-wash shrinkage and a margin of your choosing add.
Example: Front 20 × 30 × 2, Back 22 × 30 and Sleeve 12 × 24 × 2 with ½ in seams on 45 in fabric fit in three rows of 31, 31 and 25 in: 87 in = 2.42 yd, 32 % unused.
Rows across,
tallest first.
How the pieces are laid, what the seam allowance and grain settings do, how a repeat, shrinkage and extra enter the figure, and why the answer is an upper bound.
First fit, tallest first
Each piece is a rectangle — its longest and widest measurements — with the seam allowance added to every edge. The pieces are sorted tallest first and laid in rows across the fabric width: a piece goes into the first row with room left for it, or starts a new row as tall as itself. The fabric length is the sum of the row heights. This is the shelf layout a careful hand does on a cutting table, without the nesting of curved edges that a hand can add.
Grain
With the length on the grain, each piece keeps its stated orientation: width across the fabric, length along it. With either way allowed, the page turns a piece so its longer side runs across the fabric when that fits, which makes shorter rows. A piece wider than the fabric in the orientation the grain allows is reported rather than folded.
Repeat, shrinkage, extra
A pattern repeat adds one repeat to every row, the allowance for placing the motif on each piece in that row. Shrinkage is a percentage of length lost in pre-washing, so the length to buy is divided by (1 − shrinkage). Extra is your own margin, added last. All three default to none.
What the number does not settle
Pieces cut on the fold or on the bias, nap direction, matching plaids across seams, and a pattern’s own layout diagram are not modelled: the page treats each piece as a rectangle placed square on the grain. The figure is safe to buy against and usually a little more than a nested layout needs. Inputs stay in your browser; the same anonymous usage counts as the rest of the site apply.