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Quilt Calculator
Use this free quilt calculator to plan your next quilt before you cut a single piece of fabric. Pick a quilt size and a block size, and it works out the block count, the fabric yardage for the top, backing, and binding, and the batting size. It uses the standard quarter-inch seam allowance, so the numbers match the way quilt patterns are actually written.
| Material | Amount |
|---|---|
| Quilt top fabric | 8.33 yd |
| Backing fabric | 9.67 yd |
| Binding fabric | 0.76 yd |
| Batting | 98 × 116 in |
How it works
The calculator starts with the block count. It divides the quilt width by the finished block size and rounds up to get the number of blocks across, then does the same with the length to get the number of rows. A queen quilt of 90 by 108 inches with 12-inch blocks needs 8 blocks across and 9 rows down, which is 72 blocks. Because the counts are rounded up, the finished quilt may come out a few inches larger than the target size.
The quilt top yardage is worked out the way fabric is actually cut: in strips. Each block is cut a half inch larger than its finished size to allow a quarter-inch seam on every side, so a 12-inch finished block is cut at 12.5 inches. The number of blocks that fit across the fabric width is the fabric width divided by the cut block size, rounded down — three 12.5-inch blocks fit across a 44-inch width. The number of strips needed is the total blocks divided by the blocks per strip, rounded up: 72 blocks at 3 per strip needs 24 strips. Each strip is 12.5 inches long, so 24 strips is 300 inches of fabric, or 8.33 yards.
Backing is calculated separately because it is a single large piece, not a set of blocks. The backing is cut 4 inches larger than the quilt top on every side, so a 90 by 108 inch top needs backing of 98 by 116 inches. From 44-inch wide fabric, the backing is pieced from lengths: the number of lengths is the backing width divided by the fabric width, rounded up — 98 inches needs 3 lengths of 44-inch fabric — and each length is 116 inches long, so 3 lengths is 348 inches, or 9.67 yards. Wide 108-inch backing covers the whole back in one length of 3.22 yards, with no piecing.
Binding goes around the outside edge. The calculator takes the perimeter of the quilt — twice the width plus twice the length — and adds 10 inches for joining the ends and easing around the corners. A queen quilt has a perimeter of 396 inches, so 406 inches of binding is needed. Binding strips are cut across the fabric width, and each strip gives about 40 usable inches after the selvages are trimmed. Dividing 406 by 40 gives 11 strips, rounded up. At 2.5 inches wide per strip, 11 strips is 27.5 inches of fabric, or 0.76 yards.
Batting is the simplest part: buy a piece 8 inches wider and 8 inches longer than the quilt top, 4 inches of overhang on every side. That margin lets the layers shift a little during quilting without leaving a bare edge, and it also gives you something to grip while you smooth the quilt. After quilting, the excess batting and backing are trimmed flush with the top before the binding is attached.
Always pre-wash your fabric if you plan to wash the finished quilt, because cotton can shrink 3 to 5 percent, and buy all the fabric for one project at the same time, because dye lots vary.
Top yardage = strips × cut block size ÷ 36 · Backing = lengths × (length + 8 in) ÷ 36
Worked example
You are making a queen quilt, 90 by 108 inches, with 12-inch finished blocks, 44-inch wide quilting cotton, a 2.5-inch binding, and no extra allowance.
Step 1: Blocks — across: 90 ÷ 12 = 7.5, rounded up to 8. Down: 108 ÷ 12 = 9. Total: 8 × 9 = 72 blocks.
Step 2: Top fabric — cut block size is 12.5 inches. Blocks per strip: 44 ÷ 12.5 = 3. Strips needed: 72 ÷ 3 = 24. Yardage: 24 × 12.5 ÷ 36 = 8.33 yards.
Step 3: Backing — backing size is 98 × 116 inches. Lengths needed: 98 ÷ 44 = 2.2, rounded up to 3. Yardage: 3 × 116 ÷ 36 = 9.67 yards.
Step 4: Binding — perimeter is 2 × (90 + 108) = 396 inches, plus 10 inches = 406 inches. Strips: 406 ÷ 40 = 10.2, rounded up to 11. Yardage: 11 × 2.5 ÷ 36 = 0.76 yards.
Step 5: Batting — 90 + 8 = 98 inches by 108 + 8 = 116 inches.
Buy 8.33 yards for the top, 9.67 yards for the backing, 0.76 yards for the binding, and batting of at least 98 by 116 inches. If you select the 10 percent extra allowance, the calculator shows 9.17 yards for the top and 10.63 yards for the backing instead.
FAQ
How many yards of fabric do I need for a queen size quilt?
A queen quilt of about 90 by 108 inches made from 12-inch blocks needs roughly 8.3 yards of fabric for the pieced top from 44-inch wide fabric, about 9.7 yards for the backing, and about 0.8 yards for the binding. The exact amounts depend on the block size, the fabric width, and how much extra you allow for cutting and mistakes.
What is the standard seam allowance for quilting?
The standard quilting seam allowance is one quarter of an inch. Every seam in a quilt pattern assumes this amount, so a 12-inch finished block is cut at 12.5 inches to allow a quarter inch on each side. Using a different seam allowance changes the finished size of every block, so a scant quarter inch or an accurate quarter-inch foot is worth setting up carefully.
How do I calculate how many quilt blocks I need?
Divide the quilt width by the block size and round up to get the number of blocks across, then divide the quilt length by the block size and round up for the number of rows. Multiply the two numbers together. A 90 by 108 inch quilt with 12-inch blocks needs 8 blocks across and 9 rows down, which is 72 blocks in total.
How much bigger should quilt batting be than the quilt top?
Batting should extend about 4 inches beyond the quilt top on every side, so it is 8 inches wider and 8 inches longer than the finished top. This extra margin lets the layers shift slightly during quilting without leaving a bare edge, and the excess is trimmed away after quilting before the binding goes on.
How much fabric do I need for quilt binding?
Measure the perimeter of the quilt, add about 10 inches for joining the ends and turning the corners, then divide by the usable length of one binding strip, usually about 40 inches from 44-inch wide fabric. A queen quilt with a 396-inch perimeter needs about 11 strips, and at 2.5 inches wide each, that is roughly 0.8 yards of fabric.