Craft & Making
Quilt Backing Calculator
Enter quilt length and width plus fabric width to see metres of backing needed.
How much backing fabric?
Quilt backing must overhang the quilt top so you can quilt and trim square. The tool adds your extra margin on each side, then checks whether the widened quilt still fits on one width of fabric. If it does, you buy roughly the quilt length (plus margins) as a single panel. If not, it pieces panels: panels = ceil(quilt width ÷ fabric width) and metres = panels × (quilt length + margins). Wideback fabrics avoid the centre seam; standard 110 cm bolts often need two panels on a double or queen. Directional prints and matching motifs need more than this plain estimate. Related yardage planning sits in fabric meterage; cut sizes for piecing use seam allowance.
Worked example
A 200 × 150 cm quilt with 10 cm extra each side needs 220 × 170 cm. On 110 cm fabric, panels = ceil(170/110) = 2, so buy 2 × 220 cm = 4.4 m of backing (about £35.20 at £8/m).
Limits and assumptions
Does not plan directional prints, large motifs or horizontal seams. Shrinkage and squaring trim after quilting may need a little more.
Frequently asked questions
Why add extra on each side?
Backing and batting should overhang the top for basting and quilting; 8–10 cm per side is a common starting point.
When do I need two panels?
Whenever quilt width plus margins exceeds usable fabric width. Seam panels carefully and press the join flat.
Is wideback worth it?
One panel avoids a centre seam and can use less total length — compare price per metre with pieced standard width.
Does batting change backing length?
Batting should match or slightly exceed the backing plan; buy backing from the quilt-plus-margin size, not the batting label alone.