Quilt Sashing Calculator: Strips and Cornerstones
Sashing is the fabric between quilt blocks or rows. Enter the number of blocks across and down, their finished size, and the finished sashing width. You can also include cornerstone squares at the intersections of row separators.
What the layout includes
For an A across × D down grid with square finished blocks of size B and finished sashing width S, the layout adds a sashing space between adjacent blocks and rows, but no sashing around the outside. Its finished dimensions are:
- Width =
A × B + (A − 1) × S - Length =
D × B + (D − 1) × S
Each cut strip is S + ½ in wide for the two ¼ in seam allowances. The calculator counts vertical pieces between blocks and horizontal pieces between rows. With cornerstones selected, the horizontal separators are split into one sashing piece per block, with cornerstone squares at the intersections.
For example, five 12 in blocks across, six down, with 2½ in sashing finish at 70 × 84½ in before any outer border. When a piece fits across the usable fabric width, the calculator groups as many equal-length pieces as fit on one strip. A longer piece can span multiple fabric widths, joined with a ½ in allowance at each seam. Leftover fabric between different piece lengths is not counted. Cornerstone squares are reported separately within the total.
| Layout | Across/down | Block | Sashing | Finished size |
|---|---|---|---|---|
| Small grid | 3 × 4 | 10 in | 2 in | 34 × 46 in |
| Example grid | 5 × 6 | 12 in | 2½ in | 70 × 84½ in |
| Wide grid | 6 × 5 | 10 in | 3 in | 75 × 62 in |
Treat the result as a cutting estimate, not a pattern-specific cutting order. A design with sashing at the outside edges, rectangular blocks, different seam allowances or a different cornerstone construction needs its own measurements.
Source
- Finished dimensions and cut counts use the entered block grid and sashing width; seam allowances are stated calculation assumptions, and 1 yd = 36 in.