How the calculator works
The backing has to be larger than the quilt top so it never runs short while you quilt. The calculator adds the extra you enter to every side, then works out how many widths of fabric it takes to cover that size.
- Backing size = quilt width + 2 × extra, by quilt length + 2 × extra.
- Panels = how many fabric widths, joined with ½-inch seams, it takes to span the backing.
- Yardage = panels × the length of each panel, rounded up to the next ⅛ yard, the smallest cut most shops sell.
It tries both seam directions — panels running down the quilt or across it — and shows the one that needs less fabric.
Quilt backing chart for standard sizes
Based on 4 inches of extra on every side and 42 inches of usable width for quilting cotton.
| Quilt | Finished size | Backing size | 42 in quilting cotton | 108 in wide-back |
|---|---|---|---|---|
| Crib | 36 × 52 in | 44 × 60 in | 2 ½ yards (2 panels, horizontal seam) | 1 ¼ yards |
| Throw | 60 × 70 in | 68 × 78 in | 3 ⅞ yards (2 panels, horizontal seam) | 2 yards |
| Twin | 70 × 90 in | 78 × 98 in | 5 ½ yards (2 panels, vertical seam) | 2 ¼ yards |
| Full | 84 × 90 in | 92 × 98 in | 7 ¾ yards (3 panels, horizontal seams) | 2 ⅝ yards |
| Queen | 90 × 108 in | 98 × 116 in | 8 ¼ yards (3 panels, horizontal seams) | 3 ¼ yards |
| King | 108 × 108 in | 116 × 116 in | 9 ¾ yards (3 panels, vertical seams) | 6 ½ yards (2 panels) |
A king quilt is wider than 108-inch fabric once you add the extra, so it needs two wide-back panels, a strip pieced onto one panel, or 120-inch wide-back.
Example: backing a twin quilt
A twin quilt is 70 × 90 inches. With 4 inches on every side the backing must be 78 × 98 inches.
- One width of 42-inch cotton is too narrow for 78 inches, but two widths joined with a ½-inch seam give 83 ½ inches. That is enough.
- Each panel runs the length of the backing: 98 inches.
- Two panels × 98 inches = 196 inches = 5.44 yards, so you buy 5 ½ yards.
Running the panels across instead would take three panels of 78 inches (6 ½ yards), so vertical seams win for this size.
Tips before you cut
- Prewash or allow for shrinkage. Cotton can shrink 3 to 5 percent. If you prewash, add about 5 percent to the yardage.
- Trim the selvages before you sew panels together. They are woven tighter and pucker in the seam.
- Press backing seams open. It spreads the bulk and lies flatter under the quilting.
- Directional prints must run the same way on every panel. Buy a little more if the print has a large repeat you want to match.
Frequently asked questions
How much bigger should the quilt backing be than the quilt top?
Add 4 inches on every side (8 inches to the width and to the length) if you quilt on a home machine. Longarm quilters usually ask for 4 to 6 inches on each side so the frame can grip the fabric, so check with yours before you cut.
How many yards of backing do I need for a queen-size quilt?
A 90 × 108 inch queen quilt needs about 8 ¼ yards of 42-inch quilting cotton, pieced from three panels with horizontal seams, or 3 ¼ yards of 108-inch wide-back fabric with no seam.
Should the seams on a quilt back run vertically or horizontally?
Either works. The calculator picks the direction that uses less fabric. Many longarm quilters prefer horizontal seams, which lie parallel to the frame's rollers, so ask before you sew if someone else is quilting it.
What is wide-back fabric?
Quilt backing fabric woven 90 or 108 inches wide, so most quilts up to queen size can be backed with one piece and no seams. It costs more per yard but you buy far fewer yards.
Can I use a bed sheet as quilt backing?
Yes, a cotton sheet gives you a large seamless back. Choose a medium-weight percale rather than a very high thread count, which is harder to quilt through, and prewash it like any other fabric.
Last updated October 17, 2026.