Quilt Sashing Calculator
Four blocks across by five down, 25 cm blocks with 6 cm sashing, finishes 4 × 25 + 5 × 6 = 130 cm wide. Sashing goes in as two kinds of piece: the short ones between blocks come to 5 rows × 5 × 25 cm = 625 cm, and the long strips between the rows and along the top and bottom come to 6 × 130 cm = 780 cm, so 1,405 cm in all. A 107 cm fabric yields 105 cm once the selvedge is trimmed, so 14 strips, and 14 × 6 = 84 cm of fabric to buy.
Your numbers
Sashing length
1,405cm
Strips to cut
14
Fabric needed
84cm
Quilt width
130cm
Formula
Sashing length = Blocks down × (Blocks across + 1) × Block size + (Blocks down + 1) × Quilt width
The sashing width entered is the finished width. To finish 6 cm, cut 7.2 cm — two 1/4 in seams. Every short piece must be the same length, and that length is the block's cut size rather than its finished size, because the seam allowance on the block edge is still there.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Blocks acrossBlocks across. | 4 | 1 and up |
| Blocks downBlocks down. | 5 | 1 and up |
| Block size (cm)One block finished, seam allowance excluded. | 25 | 1 and up |
| Sashing width (cm)The finished width of the strip between blocks; cut it two seam allowances wider. | 6 | 1 and up |
| Fabric width (cm)The fabric width; if it is sold folded, enter the opened width. | 107 | 10 and up |
Step by step
Quick reference table
Results when only Blocks across changes and everything else stays put.
| Blocks across | Sashing length (cm) | Strips to cut | Fabric needed (cm) |
|---|---|---|---|
| 2 | 783 | 8 | 48 |
| 3 | 1,094 | 11 | 66 |
| 4 | 1,405 | 14 | 84 |
| 6 | 2,027 | 20 | 120 |
| 8 | 2,649 | 26 | 156 |
What each result means
| Result | At default values |
|---|---|
| Sashing length (cm)Short pieces and long strips added together, cut across the fabric width. | 1,405 |
| Strips to cutStrips to cut across the fabric width. | 14 |
| Fabric needed (cm)Fabric length to buy, along the grain rather than across. | 84 |
| Quilt width (cm)The finished quilt across, once bound. | 130 |
Common mistakes
The sashing width entered is the finished width. To finish 6 cm, cut 7.2 cm — two 1/4 in seams. Every short piece must be the same length, and that length is the block's cut size rather than its finished size, because the seam allowance on the block edge is still there.
Glossary
- Blocks across
- Blocks across.
- Blocks down
- Blocks down.
- Block size
- One block finished, seam allowance excluded.
- Sashing width
- The finished width of the strip between blocks; cut it two seam allowances wider.
- Fabric width
- The fabric width; if it is sold folded, enter the opened width.
- Sashing length
- Short pieces and long strips added together, cut across the fabric width.
- Strips to cut
- Strips to cut across the fabric width.
- Fabric needed
- Fabric length to buy, along the grain rather than across.
- Quilt width
- The finished quilt across, once bound.
Frequently asked questions
Q. How is Quilt Sashing Calculator calculated?
Sashing length = Blocks down × (Blocks across + 1) × Block size + (Blocks down + 1) × Quilt width — Four blocks across by five down, 25 cm blocks with 6 cm sashing, finishes 4 × 25 + 5 × 6 = 130 cm wide. Sashing goes in as two kinds of piece: the short ones between blocks come to 5 rows × 5 × 25 cm = 625 cm, and the long strips between the rows and along the top and bottom come to 6 × 130 cm = 780 cm, so 1,405 cm in all. A 107 cm fabric yields 105 cm once the selvedge is trimmed, so 14 strips, and 14 × 6 = 84 cm of fabric to buy.
Q. Can you walk through an example?
With Blocks across 4, Blocks down 5, Block size 25cm, Sashing width 6cm, Fabric width 107cm, the answer is Sashing length 1,405cm.
Q. What do I need to enter?
Enter Blocks across, Blocks down, Block size, Sashing width, Fabric width. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Blocks across moves the answer to Blocks across 2 → Sashing length (cm) 783 and Blocks across 8 → Sashing length (cm) 2,649. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The sashing width entered is the finished width. To finish 6 cm, cut 7.2 cm — two 1/4 in seams. Every short piece must be the same length, and that length is the block's cut size rather than its finished size, because the seam allowance on the block edge is still there.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.