Pick your quilt size, choose standard quilting cotton or 108″ wide backing, and the calculator tells you exactly how much fabric to buy, how many panels to cut and which way to seam them. It compares vertical and horizontal seams and picks the layout that uses less fabric.
A queen quilt (90 × 95 in) needs about 8.25 yards of standard 44/45" quilting cotton for the backing (3 panels joined with 2 horizontal seams), with 4" extra on every side. With 108" wide backing you need 2.75 yards.
Assumes 42" of usable width on 44/45" quilting cotton (40" for binding strips after seams), 106" usable on 108" wide backing, and 10" extra binding for corners and joining. Fabric amounts are rounded up to the next 1/8 yard (0.1 m).
How much backing fabric do I need? Quick chart
These amounts include 4″ of extra backing on every side, which is what most longarm quilters ask for. If you quilt on a domestic machine, you can enter a smaller margin in the calculator.
| Quilt size | Standard 44/45″ cotton | Panels / seams | 108″ wide backing |
|---|---|---|---|
| Crib (45 × 60 in) | 3 yd | 2 panels, horizontal seam | 1 1/2 yd |
| Throw (50 × 60 in) | 3 1/4 yd | 2 panels, horizontal seam | 1 5/8 yd |
| Twin (66 × 90 in) | 5 1/2 yd | 2 panels, vertical seam | 2 1/8 yd |
| Full (80 × 90 in) | 7 3/8 yd | 3 panels, horizontal seams | 2 1/2 yd |
| Queen (90 × 95 in) | 8 1/4 yd | 3 panels, horizontal seams | 2 3/4 yd |
| King (108 × 95 in) | 8 5/8 yd | 3 panels, vertical seams | 2 7/8 yd |
| California King (104 × 108 in) | 9 3/8 yd | 3 panels, horizontal seams | 6 1/2 yd (2 panels) |
How the backing calculation works
First the calculator adds the margin to each side: a 90 × 95 in queen quilt with 4″ extra needs a 98 × 103 in backing. Standard quilting cotton is sold 44/45″ wide, but after trimming the selvages you can count on about 42″ of usable width. So the backing has to be pieced from several panels.
There are two ways to piece it. Vertical seams run the length of the quilt (here 3 panels of 103″); horizontal seams run across the width (3 panels of 98″). The calculator works out both and recommends the shorter total, then rounds up to the next 1/8 yard, the smallest cut most quilt shops will sell.
Standard cotton or wide backing?
Wide backing (108″ on the bolt, about 106″ usable) lets you back most quilts up to king size with no seams at all, and it usually takes less than a third of the yardage. Standard cotton gives you far more choice of prints and lets you use fabric from your stash. For quilts wider than about 106″ in both directions, such as a California king, even wide backing needs two panels.
Finish the quilt sandwich
Once the backing is sorted, check the batting size you need, which uses the same margin, and then work out how many binding strips to cut for the edges. Making a knitted or crocheted blanket instead? Our blanket yarn calculator estimates the yardage for the same bed sizes.