🧶 Quilt Top Fabric Requirement Calculator
Enter your total block count, unfinished block size, and a waste factor for seam allowances and trimming to estimate the total fabric yardage needed for piecing your quilt top.
Square inches, converted to yards
Each block is a square of the unfinished size, the lot is inflated by the waste factor, and the total is divided by the area of a yard of your fabric:
area = blocks × size² × (1 + waste% / 100)
yardage = area / (fabric width × 36)
defaults: 20 blocks, 6 in unfinished, 15% waste, 44 in wideThat is 720 sq in of block, 828 with the waste factor, over the 1584 sq in in a yard of 44 in fabric: 0.52 yd. Unfinished means the size you cut, seam allowance included. The 44 in is full bolt width with the selvages still on, so the real figure runs higher.
Where area and cutting disagree
You do not cut area, you cut strips, and the leftover on each is lost whatever the arithmetic says:
| Block | Fit across 44 in | Width wasted |
|---|---|---|
| 4 in | 11 | none |
| 5 in | 8 | 4 in (9%) |
| 6 in | 7 | 2 in (5%) |
| 9 in | 4 | 8 in (18%) |
| 12 in | 3 | 8 in (18%) |
At 6 in the default holds up: 20 blocks are three strips of seven, 18 in, 0.5 yd against the calculated 0.52. At 12 in they need seven strips, 84 in or 2.33 yd, where the tool returns 2.09.
Frequently asked questions
What is an unfinished block size?
The size before it is sewn to its neighbours, seam allowance included. With quarter-inch seams that is half an inch over the finished size, so a 6 in unfinished block shows 5½ in in the quilt.
Is a 15 per cent waste factor enough?
It depends on how the block divides into the fabric width. A 6 in block leaves 2 in spare across 44 in and 15 per cent covers it; a 9 or 12 in block wastes 8 in on every strip, 18 per cent before a seam is sewn.
Does this include sashing, borders or binding?
No, it counts blocks only. Sashing, borders, backing and binding are worked out separately and added on.