QuiltMeasure

Quilt Backing Calculator

Enter your quilt size and fabric details to see the required backing dimensions, how many fabric lengths and panels you'll need, and exactly how much to buy.

Measurements

Measurement system

Enter inches as a decimal or fraction, like 42, 42 1/2, 42-1/2, or 1/2. In centimeters, enter a decimal like 106.5.

Backing overage

Extra fabric added beyond the quilt top's exact size on each side, so the backing extends past the quilt top edge during quilting.

The width available after excluding unusable selvage.

Fabric direction

"Selvage to selvage" means from one woven edge of the fabric to the other; "parallel to the selvages" means running the same direction the fabric unrolls off the bolt.

Nondirectional: the fabric may be rotated freely
NondirectionalNo fixed "up" — rotating the fabric doesn't matter.
Design runs along the fabric length, parallel to the selvages
Along the fabric lengthThe design's "up" direction runs parallel to the dashed selvage edges.
Design runs across the fabric width, from selvage to selvage
Across the fabric widthThe design's "up" direction runs from one dashed selvage edge to the other.

If you're not sure, check the fabric close to the selvage or the fold, or ask the retailer. Most quilting cottons are nondirectional; stripes, borders, and obvious one-way prints are the main cases where this matters.

Purchase amount

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Understanding the terms

Backing overage

Overage is extra fabric added beyond your quilt top's exact size on each side, so the backing extends past the quilt top edge during quilting. Longarm frames and basting both need that extra margin to hold the backing taut.

Usable fabric width

This is the width you can actually cut from once the selvages — the tightly woven edges running the length of the bolt — are excluded. It's usually a few inches less than the fabric's full bolt width.

Fabric lengths, panels, and seams

A fabric length is one piece cut straight across the bolt — this is what actually uses up yardage. A panel is a piece of the finished backing; a fabric length used whole is one panel, but it can also be split lengthwise into two narrower panels without using any extra fabric. A seam is where two panel edges are sewn together. The calculator always shows these three figures separately, since more panels doesn't mean more fabric, and more fabric lengths always means more seams.

Why the raw cut size stays the same, but the sewn-together size is smaller

Seam allowance is consumed only once panels are sewn together — each seam uses up a strip of fabric on both joined edges. That shrinks the assembled, sewn-together width or length, but it never changes the size you actually cut each panel to. The dimensions this calculator lists for cutting are always the raw, pre-seam sizes.

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About the results

"Least-fabric option" isn't automatically the best choice

The layout labeled least-fabric option simply uses the smallest amount of fabric among the layouts this calculator compares. Some quilters or longarm services prefer a particular seam placement regardless of cost, wide-back fabric may avoid seams entirely even if it costs more per yard, and a longarm quilter's or other service provider's stated requirements always take precedence over this general estimate.

What this calculator doesn't do

This calculator compares standard full-length backing layouts. Other piecing arrangements may use fabric differently. It does not account for matching a large or directional print's repeat across a seam — that can require additional fabric beyond this estimate. Economy piecing from shorter offcuts, scrappy or patchwork-style backings, diagonal piecing, and arbitrary fabric nesting are not included in this calculator.