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".
About this Quilt Block Size Calculator
Use this free Quilt Block Size Calculator to get quick, accurate results directly in your browser. It is designed for everyday use with no signup, no downloads, and no account required. No signup is required, and the tool works on phones, tablets, and desktop browsers.