Quilt calculator for blocks, backing and binding
Choose a quilt size or type your own and this quilt calculator works out how many blocks fit, how much fabric the blocks, sashing, border, backing and binding need, and draws the layout. It uses plain geometry and seam allowances, and it works in inches or centimetres, with yardage shown in yards and metres.
Quilts are rarely an exact multiple of the block size, so the tool tells you the nearest whole-block size to your target. Everything is calculated in your browser and nothing is stored.
How to use the Quilt Calculator
- Pick a quilt size from the list or type the width and length.
- Enter the finished block size, any sashing and the border width.
- Check the seam allowance, binding strip width, backing extra and the usable width of your fabric.
- Read the number of blocks and the fabric table; the sketch shows the quilt top.
- Copy the list to take shopping.
Quilt Calculator features
Nearest whole-block size
The grid is rounded so every block is whole, and the real finished size is shown.
Backing in the cheapest direction
It tries seaming the backing lengthwise and crosswise and keeps the shorter.
Binding and borders by strips
Strip counts come from the perimeter divided by the usable fabric width.
Yards and metres
Rounded up to the next ⅛ yard with an optional percentage for mistakes.
The method
The binding method matches the guides from Mrs Quilty, My Girlfriend’s Quilt Shoppe and Linda’s Quilt Shop (read 19 October 2026): perimeter plus 10 to 12 in for corners and the join, divided by 40 to 42 in, rounded up. The preset sizes are Missouri Star Quilt Co’s chart; other charts differ by 2 to 4 in, so quilters often size from the mattress: width = mattress width + 2 × drop.
- Blocks across = (width − 2 × border + sashing) ÷ (block + sashing), rounded to the nearest whole number; the same down the length.
- Block fabric: each block is cut as a square of the block size plus two seam allowances; squares per strip = usable width ÷ cut size, rounded down.
- Border: the sides and ends are added up, divided by the usable width and rounded up to whole strips. Binding: the perimeter plus 12 in is divided by the usable width, rounded up, and multiplied by the strip width.
- Backing: the quilt plus the extra on each side, from one wide piece or from seamed panels.
| Size | Finished (in) | Finished (cm) |
|---|---|---|
| Crib | 36 × 52 | 91 × 132 |
| Throw / lap | 50 × 65 | 127 × 165 |
| Twin | 68 × 86 | 173 × 218 |
| Full / double | 84 × 90 | 213 × 229 |
| Queen | 90 × 95 | 229 × 241 |
| King | 108 × 95 | 274 × 241 |
What it does not do
Pieced blocks with half-square triangles, flying geese or many fabrics need a calculation for each patch. The block fabric figure assumes each block is cut from squares of the same size, so treat it as an upper bound for scrappy quilts. Cotton also shrinks, and quilting pulls the top in by a few percent. Add the extra percentage if you pre-wash. For clothing see the fabric calculator for clothing, and for yarn projects the yarn calculator.
Quilt Calculator FAQ
How much fabric do I need for a quilt?
Add up the blocks, sashing, border, backing and binding. The calculator does this for any size; for a 48 × 66 in throw with 6 in blocks it comes to roughly 2⅜ yd of block fabric, 3⅜ yd of backing and ½ yd of binding.
How do I calculate quilt binding?
Add the length and width, double it, add about 12 in, divide by the usable fabric width (about 42 in) and round up to whole strips. Multiply by the strip width, often 2½ in, and divide by 36 for yards.
How big should the backing be?
Larger than the quilt top, usually by 4 in or more on every side, so it can be quilted on a frame or machine. Make it 8 in wider and longer in total.
What are standard quilt sizes?
Common finished sizes are crib 36 × 52 in, throw 50 × 65, twin 68 × 86, full 84 × 90, queen 90 × 95 and king 108 × 95, but there is no single standard.
Why is my finished size different from my target?
Blocks have to be whole, so the quilt snaps to the nearest block count. Change the border width to fine-tune it.
Does it work in centimetres?
Yes. Switch the unit and every field converts. Fabric amounts always show both yards and metres.