Quilt Fabric Calculator

What this calculator does

The Quilt Fabric Calculator helps you plan a simple patchwork quilt made from equal-sized square blocks. Tell it the finished size of your quilt, the finished size of each block, and your seam allowance, and it works out how many blocks you need and roughly how much fabric to buy. It's built for the classic straight-set grid quilt — the friendliest layout for beginners and a reliable starting point for scrap quilts.

How the math works

The number of blocks is ceil(width ÷ block) × ceil(height ÷ block), rounding up so partial edges are covered. Each block's cut size adds two seam allowances (one per side): block + 2 × seam. To estimate yardage the tool assumes a usable fabric width of 42 inches, fits as many cut blocks across that width as it can, stacks the rows, and converts the total length to yards — then rounds up to the nearest quarter yard the way a fabric shop cuts.

How to use it

1. Enter your finished quilt width and height in inches.
2. Enter the finished size of one block (e.g. 10 for a 10" block).
3. Set your seam allowance — quilters almost always use 0.25".
4. Click Calculate to see total blocks, the cut size per block, and estimated yards.
5. Buy a little extra fabric to cover shrinkage, squaring up, and mistakes.

FAQ

Does this include fabric for borders, backing, or binding?

No. It estimates the quilt top's block fabric only. Add separate yardage for backing, batting, borders, and binding.

Why round each block up?

A quilt has to fully cover the target size, so partial edge blocks are counted as whole blocks and typically trimmed to fit.

What if all my blocks are the same fabric?

The yardage shown assumes one fabric for every block. For a scrappy or multi-fabric quilt, divide the blocks (and yardage) across your fabrics.

How accurate is the estimate?

It's a planning guide, not a cutting chart. Results are estimates — always buy a bit extra and confirm your usable width before cutting.