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Sashing Calculator — Sashing Strips & Fabric
Calculate sashing strip quantities and fabric for quilt layouts.
Small squares where sashing strips meet
How We Calculate This
Sashing strips run between blocks horizontally and vertically. First the short vertical strips are sewn between the blocks in each row, then the rows are joined with horizontal sashing. The calculator counts all strips and works out total fabric.
The formula
Vertical (short) sashing = (Blocks across − 1) × Blocks down — one strip per gap between blocks, in every row.
Horizontal sashing without cornerstones = Blocks down − 1 — one long full-width strip spanning each gap between rows.
Horizontal sashing with cornerstones = Blocks across × (Blocks down − 1) — each row gap is pieced from block-length bars and cornerstone squares.
Cornerstones = (Blocks across − 1) × (Blocks down − 1) — only when cornerstones are included.
Every strip is cut its finished width plus a seam allowance on both edges (the quilting standard is a scant ¼ inch / about 0.6–0.75cm).
Frequently Asked Questions
Sashing is the fabric strips sewn between quilt blocks to separate and frame them. It creates a grid effect and can make blocks appear to float. Common sashing widths are 3-7cm finished.
Cornerstones (or setting squares) are small squares placed where sashing strips meet. They add a design element and can use a contrasting fabric. They simplify construction as you sew sashing to blocks in rows.
Sashing width depends on block size and design. A common rule is 1/6 to 1/4 of the block size. For 30cm blocks, 5-7.5cm sashing works well. Narrow sashing (2-3cm) lets blocks blend; wide sashing frames each block.
This is a design choice. Matching background fabric creates unity. Contrasting fabric frames each block distinctly. Try both options with your blocks on a design wall before cutting all sashing.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.