How much binding do I need?
Binding goes all the way round the quilt, so start with the perimeter: twice the width plus twice the length. Then add about 10 in (25 cm) for joining the strips and for the fold at each corner, and for the overlap where the two ends meet. That's the length of binding to make.
For straight-grain binding you cut strips across the fabric, from selvedge to selvedge. Quilting cotton is 42–44 in wide, but once the selvedges are trimmed you can count on about 40 in per strip. Divide the binding length by 40, round up, and that's your number of strips. Multiply by the strip width to get the fabric you need.
Binding for common quilt sizes
2.5 in strips, 10 in extra, 40 in usable width, rounded up to the next 1/4 yard.
| Quilt | Binding | Strips | Straight | Bias |
|---|---|---|---|---|
| Baby, 40 × 40 in | 170 in | 5 | 1/2 yd | 3/4 yd |
| Crib, 36 × 52 in | 186 in | 5 | 1/2 yd | 3/4 yd |
| Lap, 45 × 60 in | 220 in | 6 | 1/2 yd | 3/4 yd |
| Throw, 50 × 65 in | 240 in | 6 | 1/2 yd | 3/4 yd |
| Twin, 70 × 90 in | 330 in | 9 | 3/4 yd | 1 yd |
| Full / double, 85 × 108 in | 396 in | 10 | 3/4 yd | 1 yd |
| Queen, 90 × 108 in | 406 in | 11 | 1 yd | 1 yd |
| King, 108 × 108 in | 442 in | 12 | 1 yd | 1 yd |
| 50 × 60 in | 230 in | 6 | 1/2 yd | 3/4 yd |
| 60 × 60 in | 250 in | 7 | 1/2 yd | 3/4 yd |
| 60 × 72 in | 274 in | 7 | 1/2 yd | 3/4 yd |
| 60 × 80 in | 290 in | 8 | 3/4 yd | 3/4 yd |
The formula in plain English
- Binding length = 2 × (width + length) + 10 in.
- Strips = binding length ÷ usable fabric width, rounded up.
- Fabric = strips × strip width, rounded up to what the shop will cut (1/4 yd or 10 cm).
- Bias square = the square root of (binding length × strip width), rounded up to a whole inch.
Worked example: a 50 × 65 in throw
- Perimeter: 2 × (50 + 65) = 230 in
- Plus 10 in for joins and corners: 240 in of binding, about 6 2/3 yd
- Strips: 240 ÷ 40 = 6 strips of 2.5 in
- Fabric: 6 × 2.5 = 15 in, so buy 1/2 yd (18 in) and keep the spare 3 in for scraps
- At $13 a yard, the binding costs $6.50
- On the bias instead: 240 × 2.5 = 600 sq in, and √600 = 24.5, so cut a 25 in square and buy 3/4 yd
Binding quilts for other people? Time a throw from first cut to last stitch, then price your work per inch of binding with the free pricing worksheet, so the bigger quilts pay properly too.
FAQs
How wide should quilt binding be?
2.5 in (6.5 cm) strips are the usual choice for double-fold binding, and finish at roughly 3/8 in on the front of the quilt. Cut 2.25 in for a slimmer edge or thin batting, and 2.75 in or more for thick batting or a wider border look. Whatever you choose, keep it the same all the way round.
How do you calculate quilt binding?
Add up all four sides, add 10 in, then divide by the usable width of your fabric (about 40 in) and round up for the number of strips. Multiply the strips by their width for the fabric length. The calculator does the same and rounds up to 1/4 yd or 10 cm.
When should I use bias binding?
Use bias binding for curved edges, scallops and rounded corners: strips cut at 45 degrees stretch round curves without puckering. Many quilters also like it on heirloom quilts, because the threads cross the folded edge and wear more evenly. It takes more fabric than straight-grain binding, and the easiest way to make it is continuous bias from a square.
How much extra binding should I allow?
10–12 in (25–30 cm) on top of the perimeter is enough for most quilts. Allow more if your strips are shorter than usual, if you're using scraps with many joins, or if you like a long tail to work with when joining the ends.
Can I use metres and centimetres?
Yes. Switch the units to metric and the calculator works in centimetres and rounds fabric up to the next 10 cm.
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