Quilt binding calculator
Give it the quilt size and the binding style you sew. The calculator returns the total binding length, how many strips to cut, the yardage to buy, and the stash equivalents: how many fat quarters do the same job, and how many quilts one jelly roll binds when you cut at 2.5 in.
Length is the quilt perimeter plus 12 in for the closing join and handling. Each strip yields the usable width minus the join loss (one strip width for diagonal joins, 1/2 in for straight joins).
The formula, in words
Binding length is the quilt perimeter plus 12 in for the closing join and handling. A strip yields the usable fabric width minus what its join eats: a full strip width for a diagonal join, 1/2 in for a straight join. Strips needed is the length divided by the yield, rounded up, and the bolt is the strips times the cut width. Bias binding is different: it is an area purchase, so the calculator sizes the square you need from the strip area with a small cutting loss, and warns you when that square has to be pieced or exceeds your fabric width.
Worked example
A Queen quilt at 90 x 95 in has a 370 in perimeter, so it needs 382 in of binding. Cut at 2.5 in with diagonal joins on 44 in fabric, each strip yields 39.5 in, so 10 strips. Ten strips at 2.5 in is a 25 in bolt: buy 3/4 yd. The same binding comes out of fat quarters too, and at a 2.5 in cut one 40-strip jelly roll binds four quilts this size.
Questions quilters ask
What cut width should I use for double fold binding?
2.5 in is the common default and finishes at about 3/8 in on the front. 2.25 in finishes slimmer, near 1/4 in, and suits quilts with thin batting. 3 in gives a chunkier frame and is forgiving for beginners. The calculator lists all three as one-tap presets.
When do I actually need bias binding?
Only when the quilt edge is curved: scallops, waves, or rounded corners will not take straight grain binding without puckering. For straight edges, straight grain is stronger, stretches less, and uses less fabric.
Diagonal or straight joins?
Diagonal joins spread the seam bulk over a longer distance, so the finished binding has no lumpy spots, and they are the standard choice. Straight joins are simpler to sew and cost a little less length per strip. The calculator prices the join you pick.
Can I bind a quilt from a jelly roll?
Yes, jelly roll strips are already cut at 2.5 in, the standard double fold width. Join them diagonally, press, and sew as usual. The calculator tells you how many strips the quilt takes and how many bindings a full roll covers.