Quilt T-Shirt Quilt Calculator: T-Shirt Panels, Layout and Interfacing

How the calculator works

Step 1: Finished panel size

Finished panel size equals panel cut size minus 0.5 inch, because seam allowance 0.25 inch on each side is lost where panels join. Seam allowance is fixed at 0.25 inch on each side, as is standard for piecing, and is stated on this page, not an input. For panel cut size 12.5 inches, finished panel size equals 12.5 minus 0.5, which is 12 inches.

Step 2: Rows needed, total panels and blank panels

Rows needed equals t-shirts available divided by panels across, rounded up to a whole number, because a partial row cannot be left half empty in the layout count. For t-shirts available 20 and panels across 5, rows needed equals 20 divided by 5, which is 4 rows. Total panels in layout equals panels across times rows needed. For panels across 5 and rows needed 4, total panels in layout equals 5 times 4, which is 20 panels. Blank panels needed equals total panels in layout minus t-shirts available, because the last row may not be full, and blank panels fill it. For total panels 20 and t-shirts available 20, blank panels needed equals 20 minus 20, which is 0 blank panels.

Step 3: Finished quilt size and interfacing pieces

Finished quilt width equals panels across times finished panel size. For panels across 5 and finished panel size 12 inches, finished quilt width equals 5 times 12, which is 60 inches. Finished quilt length equals rows needed times finished panel size. For rows needed 4 and finished panel size 12 inches, finished quilt length equals 4 times 12, which is 48 inches. Interfacing pieces needed equals t-shirts available times 1, because each t-shirt panel needs one interfacing piece. For t-shirts available 20, interfacing pieces needed equals 20 pieces. Blank panels do not need t-shirt interfacing in this count unless you choose to stabilise them too, which is stated as a choice, not added to the count.

Assumptions, shown next to the result

Square panels only. Panels are cut from the front or back of a t-shirt, one panel per shirt in this count, unless a shirt gives two usable panels, in which case count panels, not shirts. Sashing is not included, use the Sashing Calculator if sashing is wanted between panels. Backing and batting are worked out with their own calculators. Finished size is after sewing, before washing, because washing does not change the sewn finished size in this calculation.

T-shirt quilt panel cut size chart

This chart uses seam allowance 0.25 inch on each side, so finished panel size equals panel cut size minus 0.5 inch.

Chart values are a guide for the cut sizes shown. Your own panel cut size may give a different result. Use the calculator above for your own measurements.

Worked example, checked against the calculator

T-shirts available 20, panels across 5, panel cut size 12.5 inches.

Finished panel size: 12.5 minus 0.5 equals 12 inches.

Rows needed: 20 divided by 5 equals 4 rows. Total panels in layout: 5 times 4 equals 20 panels. Blank panels needed: 20 minus 20 equals 0 blank panels.

Finished quilt width: 5 times 12 equals 60 inches. Finished quilt length: 4 times 12 equals 48 inches.

Interfacing pieces needed: 20 times 1 equals 20 pieces.

Second check, t-shirts available 21, panels across 5, panel cut size 12.5 inches: finished panel 12 inches, rows needed ceil of 21 divided by 5 equals 5 rows, total panels 25, blank panels 4, finished quilt 60 by 60 inches, interfacing pieces 21.

Frequently asked questions

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