How much quilt backing do I need?
Type the size of your quilt top, the extra backing you want on each side, and the width of the backing fabric. The calculator picks the layout that uses less fabric and rounds the length up to the next 1/8 yard and 0.1 meter.
- Backing to buy
- 5 yd (4.5 m)
A 60 in × 80 in quilt top needs a 68 in × 88 in backing: 2 panels, seams running the length of the quilt. Buy 5 yd (4.5 m).
- Fabric length
- 176 in
- Layout
- 2 panels, seams running the length of the quilt
- Panels
- 2
- Backing width
- 68 in
- Backing length
- 88 in
- Yards to buy
- 5
Backing to buy: 5 yd (4.5 m). A 60 in × 80 in quilt top needs a 68 in × 88 in backing: 2 panels, seams running the length of the quilt. Buy 5 yd (4.5 m).
How to calculate
Works out how much backing fabric a quilt needs: the backing size with an overhang on each side, how many panels to sew together, and the yards to buy for regular or wide backing.
Example with the default inputs (Quilt top width 60 in, Quilt top length 80 in, Extra on each side 4 in, Fabric width 42 in, Seam allowance 0.5 in): A 60 in × 80 in quilt top needs a 68 in × 88 in backing: 2 panels, seams running the length of the quilt. Buy 5 yd (4.5 m).
Method: Backing = (width + 2 × extra) by (length + 2 × extra); panels = ⌈(span − 2 × seam) ÷ (fabric width − 2 × seam)⌉ each way; buy the smaller of panels × the other side, rounded up to 1/8 yd.
- Panels are sewn side by side with one seam between neighbours; each seam uses the seam allowance on both panels.
- The fabric has no one-way print, so a panel can run either way.
- The length is rounded up to the next 1/8 yard (or 0.1 m), as fabric is usually cut.
Worked examples
Each example is checked against the calculator on every build.
- Quilt top width 60 in, Quilt top length 80 in, Extra on each side 4 in, Fabric width 42 in, Seam allowance 0.5 in gives Panels 2, Fabric length 176 in, Yards to buy 5, Backing to buy 5 yd (4.5 m), Backing width 68 in.Source: NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement (1 yard = 36 inches; 1 inch = 2.54 centimeters exactly), https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-03)
- Quilt top width 60 in, Quilt top length 80 in, Extra on each side 4 in, Fabric width 108 in, Seam allowance 0.5 in gives Panels 1, Fabric length 68 in, Yards to buy 2, Backing to buy 2 yd (1.8 m), Layout One piece, no seams.Source: NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement (1 yard = 36 inches; 1 inch = 2.54 centimeters exactly), https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-03)
- Quilt top width 90 in, Quilt top length 108 in, Extra on each side 4 in, Fabric width 42 in, Seam allowance 0.5 in gives Panels 3, Fabric length 294 in, Yards to buy 8.25, Layout 3 panels, seams running across the quilt.Source: NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement (1 yard = 36 inches; 1 inch = 2.54 centimeters exactly), https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-03)
How it works
Let the quilt top be W wide and L long, the extra on each side e, the usable fabric width F, and the seam allowance s.
- Backing size: width B_w = W + 2e, length B_l = L + 2e.
- Panels to cover a span S: each seam between two panels uses s on both, so n panels cover n × F − (n − 1) × 2s. The fewest panels are n = ⌈(S − 2s) ÷ (F − 2s)⌉, and at least 1.
- Two layouts:
- Seams running the length: n_a = panels for B_w, each cut B_l long; fabric = n_a × B_l.
- Seams running across: n_b = panels for B_l, each cut B_w long; fabric = n_b × B_w.
- The calculator uses the layout with less fabric (seams along the length on a tie). One panel is shown as "One piece, no seams".
- Length to buy: the fabric length rounded up to the next 1/8 yard (1 yd = 36 in), and to the next 0.1 m (1 in = 2.54 cm exactly).
Rules
- Sizes are typed in inches or centimeters and used as the exact decimals typed.
- The quilt top is 1 in to 500 in each way; the extra is 0 in to 50 in; the fabric 5 in to 200 in; the seam allowance 0 in to 2 in.
Worked examples by hand
60 × 80 in on 42 in cotton, 4 in extra, 1/2 in seams. Backing 68 × 88 in. Along: ⌈(68 − 1) ÷ 41⌉ = ⌈1.63⌉ = 2 panels × 88 = 176 in. Across: ⌈(88 − 1) ÷ 41⌉ = ⌈2.12⌉ = 3 panels × 68 = 204 in. Use along: 176 in = 4.89 yd, buy 5 yd; 176 in = 4.4704 m, buy 4.5 m.
The same quilt on 108 in wide backing. Along: ⌈67 ÷ 107⌉ = 1 panel × 88 = 88 in. Across: ⌈87 ÷ 107⌉ = 1 panel × 68 = 68 in. Use across: 68 in = 1.89 yd, buy 2 yd; 1.7272 m, buy 1.8 m.
90 × 108 in on 42 in cotton. Backing 98 × 116 in. Along: ⌈97 ÷ 41⌉ = 3 panels × 116 = 348 in. Across: ⌈115 ÷ 41⌉ = 3 panels × 98 = 294 in. Use across: 294 in = 8.17 yd, buy 8 1/4 yd.
Other questions people ask
How much bigger should quilt backing be than the top?
About 4 in on every side, so 8 in wider and 8 in longer than the top, is a common choice for quilting at home. A longarm quilter often asks for 4 in to 8 in on each side, because the frame clamps the backing; ask yours before you buy.
How much backing do I need for a 60 × 80 in quilt?
With 4 in extra on each side the backing is 68 × 88 in. On 42 in wide cotton that is 2 panels of 88 in, 176 in, which rounds up to 5 yards. On 108 in wide backing, one 68 in cut turned sideways is enough: 2 yards.
Should the seams run the length of the quilt or across it?
Either works. Seams that run the length are more common, but on a wide quilt, seams across can need fewer panels or shorter ones. The calculator works out both ways and shows the one that needs less fabric.
What is the usable width of quilting cotton?
Quilting cotton is sold as 44 in or 45 in wide, but after the selvages are cut off and the fabric is washed, about 40 in to 42 in is usable. Use 42 in, or measure your own fabric.
What is wide backing?
Fabric made for quilt backs, usually 108 in wide (sometimes 90 in or 120 in). It covers most quilts with no seams.
Why add the seam allowance?
Each seam that joins two panels uses the seam allowance on both of them, so two 42 in panels joined with a 1/2 in seam make 83 in, not 84 in.