Quilt Block Size Calculator
Figure out block sizes, sashing, and block counts for your quilt layout.
Common Quilt Sizes & Block Counts
| Quilt Size | Dimensions | Common Block Size | Blocks (no sashing) |
|---|---|---|---|
| Baby | 36" × 45" | 9" | 4 × 5 = 20 |
| Baby | 36" × 45" | 6" | 6 × 7 = 42 |
| Lap/Throw | 54" × 72" | 12" | 4 × 6 = 24 |
| Lap/Throw | 54" × 72" | 9" | 6 × 8 = 48 |
| Twin | 60" × 80" | 12" | 5 × 6 = 30 |
| Twin | 60" × 80" | 10" | 6 × 8 = 48 |
| Full/Double | 80" × 96" | 12" | 6 × 8 = 48 |
| Queen | 90" × 108" | 12" | 7 × 9 = 63 |
| King | 108" × 108" | 12" | 9 × 9 = 81 |
How to Use the Quilt Block Size Calculator
- Mode 1 — Find block size: Enter your quilt dimensions and how many blocks across and down you want. The calculator finds what block size you need, plus finished and unfinished measurements.
- Mode 2 — Find block count: Enter your quilt dimensions and a block size. The calculator tells you how many blocks fit and the actual resulting quilt size.
- If you add sashing, enter the finished sashing width. Sashing strips appear between blocks (and optionally on the outer edges).
Finished vs. Unfinished Block Size
- Finished size = the block size after sewing it into the quilt (seams taken).
- Unfinished size = the block size when you cut it, before sewing. Always add 0.5" (¼" seam allowance × 2 sides).
Sashing Tips
- Sashing strips separate blocks and can make a quilt larger without making more blocks.
- The number of sashing strips equals: (blocks across − 1) vertically and (blocks down − 1) horizontally for interior sashing. Add 2 more if you want outer border sashing.
- The unfinished sashing strip width = finished sashing width + 0.5".