Quilt Fat Quarter and Precut Calculator: Precuts to Piece Count

How the calculator works

Step 1: Precut size used

Precut size used is the precut type you select, for example fat quarter 18 by 22 inches, or a custom precut size you enter. Precut sizes are in inches or centimetres, depending on unit mode, and they are used as entered, with no seam allowance added.

Step 2: Pieces per precut, as entered

Pieces per precut, as entered, equals pieces across precut width times pieces along precut length, both rounded down to whole numbers, because a partial piece cannot be cut. Pieces across precut width equals precut width divided by cut piece width, rounded down. Pieces along precut length equals precut length divided by cut piece length, rounded down. For fat quarter 18 by 22 inches and cut piece 3.5 by 3.5 inches, pieces across width equals 18 divided by 3.5, equals 5.14, rounded down to 5 pieces, pieces along length equals 22 divided by 3.5, equals 6.28, rounded down to 6 pieces, and pieces per precut, as entered, equals 5 times 6, equals 30 pieces.

Step 3: Pieces per precut, rotated

Pieces per precut, rotated, swaps cut piece width and length, and repeats the same calculation. Pieces across precut width, rotated, equals precut width divided by cut piece length, rounded down. Pieces along precut length, rotated, equals precut length divided by cut piece width, rounded down. For fat quarter 18 by 22 inches and cut piece 3.5 by 3.5 inches, rotated calculation is the same, 30 pieces, because the cut piece is square. For rectangular cut pieces, as entered and rotated can differ, and the calculator chooses the larger count.

Step 4: Total pieces you can cut

Total pieces you can cut equals pieces per precut, chosen, times number of precuts you own. For pieces per precut, chosen, 30 pieces and number of precuts 4, total pieces you can cut equals 30 times 4, equals 120 pieces.

Assumptions, shown next to the result

Pieces are rectangular, cut in the stated layout, with no seam allowance added, because cut size already includes seam allowance. No extra is added for mistakes or shrinkage, because this calculator counts pieces from precuts you already own, it does not buy fabric. If your precut has a directional print and pieces must all run one way, check layout before cutting, and use the as entered orientation, not the rotated orientation, if rotation would turn the print the wrong way.

Precut piece count chart

This chart uses the same formula as the calculator: pieces per precut equals pieces across precut width times pieces along precut length, both rounded down, with the larger of as entered and rotated chosen. Cut piece is 3.5 by 3.5 inches, one precut for all rows.

Jelly roll strip and mini charm square give 0 pieces for a 3.5 inch cut piece, because cut piece width 3.5 inches is wider than precut width 2.5 inches, so no piece fits. For a smaller cut piece, those precuts can give pieces. Chart values are a guide for the precut types shown. Your own cut piece size and precut count may give a different result. Use the calculator above for your own measurements.

Worked example, checked against the calculator

Precut type fat quarter, 18 by 22 inches, number of precuts 4, cut piece 3.5 by 3.5 inches.

Pieces per precut, as entered: pieces across width 18 divided by 3.5, equals 5.14, rounded down to 5 pieces, pieces along length 22 divided by 3.5, equals 6.28, rounded down to 6 pieces, total 5 times 6, equals 30 pieces.

Pieces per precut, rotated: same, 30 pieces, because the cut piece is square.

Pieces per precut, chosen: 30 pieces, as entered orientation, tie with rotated.

Total pieces you can cut: 30 times 4, equals 120 pieces.

Frequently asked questions

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Guide for this topic: How to Calculate Fat Quarter and Precut.