Quilt Backing Calculator
Enter the finished quilt top, the overhang your quilter wants and the backing fabric width, and get backing yardage with the piecing layout, the batting pack that fits, and binding strips and yardage.
4 in for a long-arm quilter; 2 in on a domestic machine
Backing to buy
5.5 yd
78 × 98 in needed · 5.44 yd exact
Piecing
2 panels
vertical seams, each 98 in long
Batting
Full
81 × 96 in packaged
Binding
0.625 yd
9 strips × 2.5 in · 330 in around
Backing = top + overhang on all four sides, pieced with the fewest seams that fit the fabric's usable width (42 in). Binding = perimeter + 10 in ÷ (42 − 2 for diagonal joins) strips. Round up to the next eighth of a yard; buy a quarter yard extra for directional prints.
Backing, batting and binding for standard quilt sizes
Four inches of overhang, 42-inch quilting cotton, 2½-inch binding strips. The wide-backing column is 108-inch fabric.
| Quilt | Top | Backing (42") | Panels | Backing (108") | Batting | Binding |
|---|---|---|---|---|---|---|
| Crib | 36 × 52 | 2.5 yd | 2 h | 1.75 yd | Crib | 0.375 yd |
| Throw / lap | 50 × 65 | 3.25 yd | 2 h | 2.125 yd | Twin | 0.5 yd |
| Twin | 70 × 90 | 5.5 yd | 2 v | 2.75 yd | Full | 0.625 yd |
| Full / double | 84 × 90 | 7.75 yd | 3 h | 2.75 yd | Queen | 0.625 yd |
| Queen | 90 × 95 | 8.25 yd | 3 h | 2.875 yd | King | 0.75 yd |
| King | 108 × 95 | 8.625 yd | 3 v | 3.25 yd | King | 0.875 yd |
Panels: v = seams run along the length, h = across the width.
Why the overhang
A long-arm machine pins the backing to leaders at the top and bottom and clamps the sides, and the quilting draws the layers up slightly as it goes. Four inches on each side is what most quilters ask for; some want six on the leader edges. On a domestic machine you baste on a table and two inches is enough. Whatever the number, cut the backing square: an off-square back is the usual cause of puckers, and no amount of yardage fixes it.
Frequently Asked Questions
How much backing fabric do I need for a quilt?
Add 4 inches to every side of the top (8 to each dimension) for a long-arm quilter, or 2 inches if you quilt on a domestic machine. If the result is narrower than the fabric's 42 usable inches, buy one length. Otherwise piece two or three panels: the calculator tries seams running along the length and across it and keeps whichever uses less fabric. A 70 × 90 twin needs 78 × 98, which is two 98-inch panels, about 5½ yards.
How much 108-inch wide backing do I need?
One length equal to the quilt's longer dimension plus overhang, as long as the shorter dimension plus overhang fits in 106 usable inches. A queen top of 90 × 95 needs 98 × 103, so 103 inches, about 2⅞ yards, with no seam. Wide backing costs more per yard but usually less per quilt once you count the seams saved.
What size batting do I need?
A packaged size at least 2 to 4 inches larger than the top on every side. Packaged sizes are crib 45 × 60, throw 60 × 60, twin 72 × 90, full 81 × 96, queen 90 × 108, king 120 × 120. A 70 × 90 top with 2 inches of overhang needs 74 × 94, which is the full pack; the twin pack is exactly the top's size and leaves nothing to grip.
How much binding fabric do I need?
Perimeter plus 10 inches for joins and corners, divided by 40 usable inches per strip (42 less the diagonal joins), times the strip width. A 70 × 90 quilt has a 330-inch perimeter, needs 9 strips at 2½ inches, 22½ inches of fabric, so ⅝ yard. Cut binding on the straight grain across the width unless the edges are curved, when bias binding needs about 50% more.
Which way should the backing seam run?
Whichever uses less fabric, which the calculator works out, unless the print is directional. Horizontal seams on a large quilt often save a yard because two 78-inch panels are shorter than two 98-inch ones. Trim the selvedges before seaming and press the seam open to reduce bulk under the quilting.
These tools use the standard craft-room rules (resin volume by area and depth, quilt overhang and width-of-fabric piecing, yards per square inch by yarn weight, wax weight per fluid ounce, gauge ratios), all stated on each page. Materials vary by brand: check your resin's mix ratio, your wax's fragrance limit and your own swatch, and buy a little over.