Quilt Binding Calculator

How the binding calculation works

First, find the perimeter: add the width and length, then double it. A 60 x 80 in quilt has a perimeter of 280 in. Next, add extra for mitered corners and for the join where the two ends meet. This tool defaults to 12 in, which gives 292 in in total. Some quilters like a little more, and you can change this figure.

Next, work out what each strip gives you. A strip cut across 42 in fabric would add 42 in, except that joining strips on the diagonal uses about one strip width of length per join. With 2 1/2 in strips, each adds about 39 1/2 in. So 292 divided by 39 1/2 is 7.4, which rounds up to 8 strips. Eight strips at 2 1/2 in each is 20 in of fabric, or 5/8 yard once it is rounded up to the next 1/8.

What width should you cut quilt binding?

The most common width for double-fold binding is 2 1/2 in. Folded in half and sewn with a 1/4 in seam, it wraps the edge to give a finished width of about 3/8 in. This forgiving size suits most quilts, and it is a good default for a beginner, since a slightly wider strip is easier to turn neatly to the back.

Many experienced quilters prefer 2 1/4 in for a narrower, crisper edge, particularly on a thin cotton batting. Thick or wool battings take up more of the strip as it turns over the edge, so they may call for a wider strip. If you are unsure, try a short length on a sample sandwich made from your actual batting and fabrics. A few minutes of testing here can save you from unpicking the whole edge.

Straight-grain or bias binding?

Straight-grain strips, cut across the width of the fabric, are the most economical and they work well on quilts with straight edges and square corners. The cross-grain has just a little give, which helps the binding lie flat. This calculator covers that method, and the chart below it shows typical figures for common quilt sizes.

Bias binding is cut at a 45-degree angle, and it stretches enough to follow curves and scallops. It also wears better along a folded edge, which some quilters want for a quilt that will be used and washed often. A stripe or plaid cut on the bias makes an attractive candy-cane effect too. It takes more fabric, so allow extra if you choose it. Our guide to bias binding explains how to use it.

Joining and attaching binding strips

Join strips with a diagonal seam rather than a straight one. Lay the two strip ends right sides together at a right angle, sew from corner to corner, then trim the seam to 1/4 in and press it open. The diagonal seam spreads the bulk along the binding, so it will not make a lump when you fold the strip in half and wrap it around the quilt edge.

Press the long strip in half lengthwise with wrong sides together, then sew the raw edges to the front of the quilt. Leave a tail of about 10 in at the start, which is one reason the calculator includes extra length. Stop 1/4 in from each corner, fold the strip to form a miter, and carry on down the next side. Join the ends, then turn the fold to the back and stitch it down by hand or by machine.

Using leftover fabric for binding

Binding uses a small amount of fabric, so it is a good place to use what you have left from a project. The strips do not all have to match. A scrappy binding made from several prints in your quilt can look deliberate and charming, as long as you cut them all to the same width. Try the strips against the quilt top before you commit, and vary the colors around the edge so that the eye keeps moving.

Fat quarters work too, though each strip is shorter, so you will need more of them. Cut across the 21 in side, and divide your total length by about 18 1/2 in per strip to find out how many you need. Our fat quarter calculator can tell you how many strips each fat quarter gives. Whatever you use, round up: running out of binding is always more trouble than a small piece left over.

Common binding mistakes to avoid

The first is forgetting to trim the quilt before you measure it. Quilting draws the layers in, so a quilt can finish an inch or two smaller than the pattern says. Measure after you have squared up the edges, since this is the distance your binding really has to cover. Another common mistake is starting the binding at a corner. Start partway along a side instead, so that the final join falls somewhere straight and easy to sew, and try to keep the joins away from the corners, where bulk causes trouble.

Uneven width is another problem, and it usually comes from cutting with a dull blade or letting the ruler slip. Fold and press the strip carefully, so that both raw edges line up, and check that your seam allowance stays the same. If your binding looks wavy, you may have stretched it as you sewed. Let the machine feed it through instead of pulling. If you are binding a large quilt by hand, use clips rather than pins so that nothing scratches you as you work, and try to sew a little at a time, since this makes the job feel far more manageable.