Fat quarter calculator
Tell it your quilt size, block size and precut type, and it counts the precuts you need for the quilt top.
Enter your numbers
How it is calculated
The quilt is divided into blocks: width and length are each divided by the finished block size and rounded up, and the two counts multiplied give the number of blocks. Each block is cut 1/2 in larger than finished for seam allowances.
Each precut yields a fixed number of those cut squares. The tool uses conservative usable sizes (a fat quarter as 20 x 17 in after squaring, a fat eighth as 20 x 8, charm squares 5 in, layer cake squares 10 in, jelly roll strips 2 1/2 x 40 in), so real precuts should never come up short. Blocks divided by squares-per-precut, rounded up, is your answer. The yardage equivalent uses the total cut area plus a 10 percent cutting allowance.
Worked example
A 60 x 72 in throw in 6 in finished blocks is 10 x 12 = 120 blocks, cut at 6 1/2 in. A fat quarter yields 6 of those squares, so you need 20 fat quarters. In layer cake squares it is 120 slices, which is 3 packs of 42. From yardage the same top takes about 3 7/8 yards.
Common questions
- How many fat quarters do I need for a throw quilt?
- For a 60 x 72 in throw in 6 in blocks, 20 fat quarters cover the top. Bigger blocks need fewer: the same throw in 8 in blocks takes about 17. Enter your exact size above for a real count.
- What size is a fat quarter?
- Nominally 18 x 21 in, which is a half yard cut in half the other way. After trimming and squaring you can rely on about 17 x 20 in of usable fabric, which is what this calculator assumes.
- How many squares are in a charm pack or layer cake?
- Both typically hold 42 squares: 5 in squares in a charm pack and 10 in squares in a layer cake. Brands occasionally vary, so check the wrapper.
- Why does it say my block does not fit a jelly roll?
- Jelly roll strips are only 2 1/2 in wide, so the largest square you can cut is a 2 in finished block. Jelly rolls really shine in strip-pieced designs like rail fence and log cabin, where you sew strips together before cutting.
- Does the count include borders, sashing or backing?
- No, only the pieced top. Use the border calculator and backing calculator for those, then add everything up.
Related tools
SewCalc results are careful estimates based on standard practice. Fabrics, brands and personal technique vary, so always confirm measurements against your own pattern or project before cutting.