Quilt Binding Calculator - Binding Length and Yardage from Perimeter

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The last step that always surprises quilters

Binding is the final step of a quilt, and it is the step most often underestimated. After weeks of piecing, the quilter measures the quilt, guesses at the binding, and discovers the strips run out three quarters of the way around. This calculator prevents that. Enter the quilt size, the binding strip width and the usable fabric width, and it returns the perimeter, the total binding length including joins, the number of strips to cut, and the yardage to buy.

The maths has one part people forget: the joins. Binding strips are sewn together end to end before they are attached, and each diagonal join eats a little length. The calculator adds 12 inches for joins and for the overlap where the binding ends meet. On a large quilt that allowance matters, because a binding that is exactly the perimeter long will always come up short once the joins are sewn.

How to use the calculator

Measure the finished quilt width and length in inches, after quilting.
Choose the binding strip width. Two and a half inches is the standard for double-fold binding.
Enter the usable fabric width, usually 42 inches for quilting cotton.
Read the strip count and the yardage. Cut that many strips, and join them with diagonal seams.

A worked example

Take a quilt of 60 by 80 inches. Its perimeter is 280 inches, and with 12 inches for joins the binding must be 292 inches long. At a 42 inch usable width, that needs seven strips, because six strips give only 252 inches. Seven strips at 2.5 inches wide use 17.5 inches of fabric length, which is 0.49 yards, so buy half a yard. Shops cut in eighth-yard steps, so half a yard is exactly right.

Compare a table runner of 20 by 60 inches. Its perimeter is 160 inches, plus 12 is 172, which needs five strips at 42 inches, or 0.35 yards. A fat quarter is not enough for most bindings: it gives only one 22 inch strip direction, so check the strip count before assuming a leftover will do.

Tips for clean binding

Cut strips on the straight grain for a firm edge, or on the bias for a quilt with curved edges.
Join strips with diagonal seams. They lie flatter than straight seams and spread the bulk.
Press the binding in half lengthwise before attaching it, and press the joins open.
Always make one strip more than the calculator says if the fabric is directional or if you are new to binding.

Common mistakes

The most common mistake is measuring the quilt top before quilting. Quilting shrinks a quilt slightly, and binding cut for the pre-quilting size will be too long rather than too short, which is the better error, but it still wastes fabric. Measure after quilting for the true number. Another mistake is forgetting the join allowance, which is exactly what this calculator adds for you.

Another trap is cutting strips from a fat quarter bundle without checking the length. A fat quarter is 18 by 22 inches, so its longest strip is 22 inches, and a large quilt can need a dozen of them. Yardage is cheaper and simpler for binding, and one continuous cut avoids a pile of short joins.

Who uses a binding calculator

Quilt shops use it at the cutting counter when a customer finishes a quilt and needs binding fabric today. Pattern designers use it to write binding requirements that do not leave buyers short. Beginners use it to buy binding with the same confidence as the rest of the quilt. Finish the quilt properly: the binding is the frame, and a good frame deserves enough fabric.

Quilt Binding Calculator – Binding Length and Yardage from Perimeter