Quilt Backing Calculator
Enter your quilt top's width and length and get exact backing yardage for any fabric width — the calculator compares vertical and horizontal seam layouts, picks the cheaper one, and estimates binding strips at the same time.
Calculate backing & binding yardage
Works for 42–44" quilting cotton, 60", 90", 108" and 120" wide backings.
How quilt backing math works
Backing must be a few inches bigger than the quilt top on all sides — the layers shift slightly during quilting and longarm machines need extra to clamp onto. Then it is just a coverage problem:
Piece the lengths together with a ½-inch seam, pressed open, and remove selvedges before sewing — selvedges are woven tighter and can pucker after washing.
Worked example
60 × 80 inch quilt top, 4 inches of overage, 42-inch quilting cotton:
Switch to 108-inch wide backing and the whole quilt is covered by one 68-inch length — just 1⅞ yd with no seams at all. That is the power of wide backing on quilts up to about 100 inches wide.
Common quilt sizes — quick reference
| Quilt | Finished size (in) | Backing @ 42 in | Backing @ 108 in |
|---|---|---|---|
| Baby | 36 × 48 | 2⅞ yd | 1⅝ yd |
| Lap / throw | 52 × 65 | 4⅛ yd | 2 yd |
| Twin | 64 × 86 | 5¾ yd | 2½ yd |
| Queen | 84 × 92 | 7⅝ yd | 2¾ yd |
| King | 100 × 92 | 7⅞ yd | 3 yd |
These assume 4 inches of overage per side. The calculator handles any custom size — and always re-check your quilter's requirements if you send tops out.
Frequently asked questions
How much backing fabric do I need for a quilt?
Take your quilt top's width and length, add 4–8 inches of overage on each dimension, then compute how many fabric-width lengths it takes to cover the wider dimension. A 60×80 inch quilt in standard 42-inch quilting cotton needs about 5¾ yards of backing (pieced from lengths); the same quilt in 108-inch wide backing fabric needs only 2½ yards with no seams.
How much overage should quilt backing have?
Home quilters: 4 inches extra on every side covers longarm clamping and slight straightening. If you send to a longarm service, they typically require 8 inches total per side — check your quilter's requirement before buying.
Should quilt backing seams run vertical or horizontal?
Run seams parallel to the quilt's longer side when possible: fewer seams, less bulk, and the seam hides in the fold shadow. The calculator compares both layouts and picks the one that needs less fabric.
How much binding fabric do I need?
Binding length is the quilt perimeter plus about 10 inches for joins and corners. Divide by your usable strip width (about 40 inches for 42-inch cotton) to get the number of 2.5-inch strips, then convert to yardage. A 60×80 inch quilt needs about ⅝ yard of binding fabric.
Is 108-inch wide backing fabric worth it?
For quilts wider than about 60 inches, usually yes. Wide backing eliminates seams, saves piecing time, and often costs less per square inch despite a higher per-yard price.