gizmobench

Quilt Binding Calculator

A 60 by 80 quilt has a perimeter of 2 x (60 + 80) = 280 in, and with the usual 10 in allowance for turning the four corners and joining the two ends it wants 290 in of binding. What this calculator does differently is pay for the joins before it counts the strips: joining one strip to the next on the diagonal costs the strip width plus the two quarter inch seam allowances, which is 3 in on a 2.5 in strip, so seven 44 in strips give 290 in of binding rather than 308 in. That is 7 strips, 17.5 in off the bolt, 0.5 yd. Dividing the perimeter by the fabric width instead, the way a quick answer does it, is how a quilt runs out of binding a hand span from the end. Choose bias and the same quilt comes off one 28.5 in square as a single continuous strip, 0.875 yd, and on 108 in wide backing it takes 3 strips. Measurements read as decimals or as fractions such as 2 1/4, the method is printed beside the answer, and the cutting sheet copies in one press.

Quilt 60 x 80 inBinding 2.5 inFabric 44 in
quilt          60 x 80 in
perimeter      280 in    2 x (60 + 80)
allowance      10 in    corners and joins
needed         290 in

strips         7    cut 2.5 in wide across 44 in
joins          6    diagonal, 3 in each
binding        290 in    0 in spare
fabric         17.5 in off the bolt
yardage        0.5 yd    (1/2 yd, 2.5 in cuts)
Perimeter280 in
Strips7at 44 in
Yardage0.5 yd1/2
Width2.5 in

strips = ⌈(290 − 3) ÷ (44 − 3)⌉ = 7. Cut 7 strips 2.5 in wide across the 44 in fabric, and join them end to end with 6 diagonal seams: about 290 in of binding from 17.5 in off the bolt. The perimeter is 2 x (width + height), the allowance you set is added to it, and every diagonal join costs the strip width plus the two quarter inch seam allowances, which is 3 in here. Strips round up to a whole strip and yardage rounds up to the next eighth of a yard, so the figure is never short: buy more for a print you want to match, or for a fabric that shrinks in the wash.

The same quilt, three ways

Straight grain is the usual cut and the thriftiest. Bias stretches around a curved or scalloped edge, and comes off one square as a single continuous strip. Wide backing fabric gives strips long enough to need far fewer joins.

  • Straight grain44 in fabric, strips joined end to end, the one on the stage
    7 strips, 0.5 yd
  • Bias cutsame quilt, one continuous strip off a square
    1 continuous strip off a 28.5 in square, 0.875 yd
  • 108 in backingsame quilt, straight grain on wide goods
    3 strips, 0.25 yd
Accuracy. Exact arithmetic on the measurements you enter, rounded up to whole strips and to the next eighth of a yard. It adds the allowance you set for corners and joins, and assumes straight-grain strips unless you choose bias. The binding it counts is the length of strip, not the fold: how much of that width finishes on the front of the quilt depends on your seam allowance and your press.

Common questions

How much binding do I need for a quilt?
Measure the finished quilt, add the four sides, then add a little for turning the corners and joining the two ends. A 40 by 60 crib quilt has a 200 in perimeter, and with the standard 10 in allowance it wants 210 in of binding. Cut 2.5 in wide from 44 in quilting cotton that is 6 strips, because six strips joined by five diagonal seams give 249 in and five strips would only give 208 in. That is 15 in off the bolt, or half a yard once it is rounded up to the next eighth.
How many 2.5 inch strips do I need for quilt binding?
It depends on the perimeter and on how long each strip is, and the joins have to be counted. A strip joined to the next one on the diagonal loses the strip width plus the two quarter inch seam allowances that get trimmed away, so a 2.5 in strip costs 3 in at every join. For a 60 by 80 quilt needing 290 in of binding off 44 in fabric, seven strips give 7 x 44 minus 6 x 3, which is exactly 290 in: 7 strips. The calculator counts the strips after that loss rather than before it, which is the difference between a binding that reaches and one that does not.
How much fabric does quilt binding take?
Each strip is cut across the usable width of the fabric and takes its own width off the length of the bolt, so the fabric is the strip count times the cut width. The 60 by 80 example is 7 strips at 2.5 in, which is 17.5 in, and that rounds up to 0.5 yd because an eighth of a yard is the smallest cut most shops will make. The same quilt off 108 in wide backing needs only 3 strips, which is 7.5 in of fabric, or 0.25 yd. Nothing is ever rounded down.
How much extra should I add for corners and joining the ends?
Ten inches is the usual working figure and it is what the Extra field opens with: a few inches for the mitres at the four corners, and enough tail at each end to join the binding into a loop. The field is yours to change. Set it to 12 or 15 if you like a long tail to join, or to 0 to see the bare perimeter. Whatever you enter is added to the perimeter before any rounding happens, and the cutting sheet shows the perimeter and the allowance on separate lines so you can see which is which.
How do I work out continuous bias binding?
Continuous bias comes off one square: cut it corner to corner, join the two triangles, sew the result into a tube offset by one strip width and cut one long spiral. A square of side S cut at strip width w yields roughly S x S / w minus S inches, so the tool solves that for S and rounds up to the next half inch. The 60 by 80 quilt needing 290 in of 2.5 in binding comes off a 28.5 in square, which is 0.875 yd, and the two seams that build the tube are paid for in the arithmetic. Bias stretches, so it is the cut for curved and scalloped edges, and it costs more fabric than straight grain. If the square comes out wider than your fabric, the page says so instead of quietly giving you a number you cannot cut.
Should the binding strips be 2.25 or 2.5 inches wide?
Both are common: 2.5 in is the usual double fold width, and 2.25 in gives a snugger finish on a thin quilt. Enter the width you actually cut and everything follows from it, including the loss at each join, which is 3 in for a 2.5 in strip and 2.75 in for a 2.25 in strip. The calculator counts the length of strip you cut, not how wide the fold finishes on the front of the quilt: that depends on your seam allowance and your press.
Can I type fractions, and does it work in centimetres?
Fractions read the way you write them on a cutting plan, so 2 1/4, 2-1/4 and 1/2 all parse, and so does a decimal or a number with in or an inch mark after it. The calculator works in inches and yards throughout, because the eighth of a yard it rounds to is an imperial cut. For a metric project, convert your measurements first, or use the strips figure with your own fabric width.
Does anything I type here leave my browser?
No. The arithmetic runs in the page, there is no account and nothing is uploaded. Your last set of measurements is kept in this browser so the numbers are still there after a reload, and if storage is blocked the calculator still works: it opens on the worked example each time.

Exact arithmetic on the measurements you enter, rounded up to whole strips and to the next eighth of a yard. It adds the allowance you set for corners and joins, and assumes straight-grain strips unless you choose bias.