Quilt Backing Calculator — Yardage for Single or Pieced Backing
Enter your finished quilt size, the usable width of your backing fabric, an overage allowance per side (4″ is common for longarm quilting), and an optional shrinkage %. The calculator tells you whether one piece is enough or you need a pieced backing, plus exact and purchase yardage.
What this calculator determines
It calculates the backing yardage for a quilt — whether a single piece suffices or a pieced backing is needed — plus exact and purchase yardage from quilt size, fabric width, overage, and shrinkage.
Related calculators
Quilt Size Calculator
Finished quilt dimensions from block size, layout, sashing, and borders
Quilt Batting Calculator
Minimum batting size needed and the smallest common pre-cut batting that fits
Quilt Binding Calculator
Binding strip count and yardage from quilt perimeter, cut width, and WOF
Fabric Yardage Calculator
Yardage needed to cut a quantity of same-size pieces from fabric of any width
Beginner Quilt Planner
Plan a first quilt: finished size, block layout, and a full shopping list
Examples
Throw quilt, 42″ fabric
60″ × 72″ quilt, 42″ fabric, 4″ overage, 0% shrinkage, 0.5″ seam loss
Calculation
- Needed: 68″ × 80″
- 42″ fabric < 68″ and < 80″ → must be pieced; usable panel width = 42 − 0.5 = 41.5″
- Side by side: ceil(68 ÷ 41.5) = 2 panels × 80″ = 160″
- Stacked: ceil(80 ÷ 41.5) = 2 panels × 68″ = 136″ ← less fabric
- Yards: 136 ÷ 36 = 3.778 → buy 3.875 yd
Buy 3.875 yards (2 stacked panels)
Wide backing, single piece
60″ × 72″ quilt, 108″ fabric, 4″ overage
Calculation
- Needed: 68″ × 80″
- 108 ≥ 68 → single piece
- Yards: 80 ÷ 36 = 2.22 → buy 2.25 yd
Buy 2.25 yards (single piece)
Assumptions & Conventions
- Overage
- Overage is added to both sides of each dimension (default 4″ per side) for longarm loading.
- Shrinkage
- An optional shrinkage percentage inflates the needed size so the backing is large enough after prewashing.
- Usable fabric width
- Defaults to 42″ and can be changed to match your fabric (e.g. 108″ wide backing).
- Seam loss
- Each panel seam loses 0.5″ of usable width by default.
- Pieced layout
- Auto chooses the layout — side-by-side or stacked — that uses the least fabric; either can be forced.
- Purchase rounding
- Purchase yardage is rounded up to the next 1/8 yard; exact yardage is shown separately.