Quilt backing calculator
Enter the finished size of your quilt top. The calculator adds the overhang, tries vertical and horizontal seams, and shows how much fabric to buy.
How the backing is worked out
The backing must be larger than the quilt top so it can be loaded on a frame and so nothing runs short while quilting. The calculator adds your overhang to every side, then checks how many widths of fabric are needed:
- Vertical seams: panels run the length of the quilt. Panels = the fewest widths of fabric that cover the backing width once each seam has taken 1" (a ½" seam). Fabric = panels × backing length.
- Horizontal seams: panels run across the quilt. Panels = the fewest widths that cover the backing length, again allowing 1" per seam. Fabric = panels × backing width.
The cheaper option is shown first, rounded up to the next ⅛ yard (or 0.1 m). Buy a little extra if your fabric has a directional print you want to match across the seam.
Frequently asked questions
How much bigger should quilt backing be than the top?
Most longarm quilters ask for 4 to 6 inches extra on every side (8 to 12 inches added to the width and length). For quilting on a domestic machine, 2 to 4 inches per side is usually enough.
Why does the calculator use 42 inches for 44/45 inch fabric?
After you trim the selvages and allow for shrinkage, standard quilting cotton gives about 40 to 42 inches of usable width. Using the full 44 inches is a common reason for a backing coming up short.
Should backing seams run vertically or horizontally?
Either works. The calculator works out both and picks the one that needs less fabric. Longarm quilters often prefer horizontal seams, so check with yours before you sew.
When is wide backing fabric worth it?
Wide backing (108 inches) lets most quilts up to queen size be backed in one piece with no seams. It usually costs more per yard, but you buy fewer yards and skip the piecing.
More calculators
- Quilt binding and border calculatorStrips and yardage for binding and borders.
- Quilt size calculatorFinished quilt size for any bed, drop and pillow tuck.
- Quilt batting calculatorBatting size and which package fits.
- Quilt block calculatorHow many blocks or squares, with or without sashing.
- Half square triangle (HST) calculatorCut sizes and square counts for 2, 4 and 8 at a time.
- Fat quarter and fabric cutting calculatorSquares per fat quarter or yard, and how many to buy.
- Printable hexagon templateHexagon sheets for EPP at true size, with seam allowance.
- Printable applique templatesHearts, stars, flowers and more, printed at any size.
- Quilt label templateType your label, preview it and print at true size.
- Increase or decrease evenly calculatorWritten instructions for “increase evenly across the row”.
- How much yarn do I need?Yardage and skeins by project and yarn weight.
- Gauge and yarn amount calculatorConvert a pattern to your gauge and count skeins.
- How many stitches to cast onStitches to cast on for any width and gauge.
- Picking up stitches calculatorEven pick-up instructions for edges and bands.
- Temperature blanket plannerTemperature ranges, a colour for each and a printable chart.
- Row counterTap to count rows; remembers where you were.
- Crochet blanket sizes and starting chainBlanket size chart and how many chains to start with.
- Yarn grams to length calculatorGrams to metres or yards (and back) from the label.
- Amigurumi ball (sphere) calculatorRound-by-round crochet ball pattern for the size you want.
- Cross stitch fabric calculatorFinished design size and fabric to cut for any count.
- Pattern from imageTurn a photo into a stitch chart with a colour legend.
- Embroidery floss calculatorHow many skeins of floss per colour, from the stitch count.
- Quilt and craft pricing calculatorMaterials, time and longarm cost into a fair selling price.
- Macrame cord calculatorCord length per strand and in total for wall hangings, plant hangers and bags.