How to use the fat quarter cutting calculator
- Enter the width and height of the piece to cut, including seam allowance.
- Enter how many pieces you need to count the fat quarters to buy.
- Open More options to change the fat quarter size, since the 18 by 22 inches shown is an example, or to remove trim from each edge.
- Read the pieces per fat quarter, the layout and the share of fabric used.
Formula
across = floor(fat quarter width / piece width)
down = floor(fat quarter height / piece height)
pieces = across x down, tried with the piece turned, keeping the larger
fat quarters = pieces needed / pieces per fat quarter, rounded up
The layout is a straight grid of identical pieces. Mixed layouts can fit more in some cases.
Five inch squares
In an 18 by 22 inch fat quarter, 18 / 5 = 3.6 gives 3 across and 22 / 5 = 4.4 gives 4 down, so 12 squares fit, using 12 x 25 = 300 of the 396 square inches, or 75.8%. Twenty-five squares need 25 / 12 = 2.08, so 3 fat quarters.
A 2.5 by 6.5 inch strip fits 7 across and 3 down, which is 21 pieces. A 4 by 9 inch rectangle fits 8 one way but 10 when turned (4 across and 2 down gives 8, while 2 across and 5 down gives 10), so 50 pieces need 5 fat quarters.
Fat quarters are not all the same size
A fat quarter is a half yard of fabric cut in half again, so it is wide and short instead of a long strip. The exact size depends on the width of the fabric and how it was cut, and it can shrink after washing. Measure your own and enter it in More options for a reliable count.
Selvedges and ragged edges may need to come off before cutting. Use the trim box to take that off every edge at once.
Where to go next
Plan blocks with the Quilt Block Size Calculator and triangles with the Half Square Triangle Calculator. For larger yardage, use the Fabric Yardage Calculator and the Quilt Backing and Binding Calculator.
Assumptions and limits
- The fat quarter is a plain rectangle of the size you enter.
- Pieces are the same size and are cut in a straight grid, with the piece tried both ways round.
- Directional prints may need all pieces turned the same way, which can lower the count.
- Trim is removed evenly from all four edges.
Frequently asked questions
How many squares can I cut from a fat quarter?
Divide the width and the height of the fat quarter by the size of the square, round each down, and multiply. Five inch squares from an 18 by 22 inch fat quarter give 3 by 4, or 12 squares.
How big is a fat quarter?
A common size is about 18 by 22 inches, but it varies with the fabric width and the cut. Enter your own measurements in More options.
Should I turn the piece to fit more?
The page tries both ways and keeps the larger count. If your print has a direction, check the layout against it.
How many fat quarters should I buy?
Divide the pieces you need by the pieces per fat quarter and round up. Buy one extra if the fabric is hard to match later.