Choose a block grid or a target size
For a known grid, enter columns and rows plus the finished square block size. To cover a target, switch to minimum target size: the calculator chooses the smallest whole number of columns and rows that reaches each dimension, with your sashing and border included. It may exceed the target because blocks stay whole. All calculations run in your browser; nothing is uploaded.
Worked example: thirty-five 9-inch blocks
A 5-column by 7-row layout has 35 blocks. With 2-inch inner sashing, the center is 5 × 9 + 4 × 2 = 53 inches wide and 7 × 9 + 6 × 2 = 75 inches long. A 3-inch border on each edge gives a planned finished top of 59 × 81 inches. With a quarter-inch seam, its unbound outer edges measure 59½ × 81½ inches. Changing the target to 60 × 80 inches needs 6 columns and 7 rows, giving 70 × 81 inches; five columns miss the width by one inch.
Read the preparation list before cutting
The block row lists already prepared, unfinished blocks: a 9-inch finished block is 9½ inches before joining at a quarter-inch seam. It does not describe the small pieces inside a patchwork block. Vertical sashing joins blocks within each row; full-width horizontal strips join the rows. No cornerstones are included. For the example, prepare 28 short sashing strips and 6 continuous row strips, then attach side borders before top and bottom borders.
What this plan can and cannot tell you
This is a straight-set layout of equal square blocks, internal sashing and one equal-width border with square corners. It does not handle on-point settings, mitered borders, mixed block sizes, quilting take-up or washing shrinkage. The diagram shows every block up to 400 blocks, then a simplified overview. Each axis is limited to 100 blocks. Long strips may need piecing: the listed lengths do not include those join losses or decide how much fabric to buy.
References and further reading
Examples and calculations are explained above; follow your pattern and measure your own materials before cutting.