Calculating Binding and Backing Materials

You just finished a quilt top and are elated! Then, you realize you need to find a backing material because it didn’t come with the kit you bought. Then, you have to bind it…. Shopping for the material will be fun if you don’t have enough in your stash. Then, again maybe you do but need a good excuse to fabric shop anyway. Regardless, you need to know how much to buy or use from your stash.

One important note – if you have prewashed your quilt top fabrics, make sure to also wash your backing fabric and add 10% extra fabric to account for shrinkage.

Let’s start with the backing. First, determine how it will be quilted. I know this sounds like the odd place to start, but it does matter. If it will be quilted by hand or by a domestic machine, add 4-6 inches to the length and width of the quilt top. This provides enough extra fabric if the back shifts or it isn’t quite square. If it will be quilted by longarm, add 10-12 inches to the length and width of the quilt top.

Why? Longarm quilt machines need that extra material as “leaders” to stretch the quilt between the bars. If there isn’t enough extra fabric, leaders need to be sewn onto the quilt (extra time and cost) to ensure the longarm has enough room to quilt the entire top without hitting pins. Trust me, I did it while learning to use my longarm, hitting a pin will put a longarm out of commission until the technician arrives to fix it.

Backing dimensions for hand quilting or domestic machine quilting: Quilt Top Width + 6-inches and Quilt Top Length + 6-inches.

Backing dimensions for longarm quilting: Quilt Top Width + 12-inches and Quilt Top Length + 12-inches.

Great, now we know the dimensions of the backing, but what does that translate into for yardage? Excellent question. The answer is that it depends upon the fabric width. Most quilting fabric is assume to be 40-inches wide. This is great for small quilts (one dimension <40-inches).

You can also buy backing fabric, which is 108-inches wide. Backing fabric often has a more limited design selection, but is wonderful for large quilts (one dimension >79-inches) since it doesn’t need to be pieced. Backing fabric is a bit of a waste for small projects.

So we have a Goldilocks situation, too small or too big. How do we get just right? To get just right, the backing needs to be pieced together with 1/2-inch seam. The following figure shows how to calculate backing. Remember to consider the cost of standard fabric versus backing fabric.

Batting sizes should be at least as large as the backing size used.

Now, you have your gorgeous quilt stitched together and you are ready for the final step – binding the quilt. How much fabric will you need for that? There is a quick calculation.

Number of strips = ((2 x length in inches) + (2 x width in inches) + 12 1/2-inches)/40-inches {round up to next whole number}

Yardage = (Number of strips x 2.5-inches)/36-inches

This assumes standard 2 1/2-inch strips for binding, 2 1/2-inch overlap and 2 1/2-inches for each corner. It also assumes you will lose about 2 1/2-inches for each mitered seam of the binding strips. Some people use narrower or wider bindings. If you are using piping, prairie points, curves or other fancy edging, this calculation may not work.

Many online fabric shops have calculators for you to use. Some of them account for using partial widths for backing. So verify how they are calculating that yardage. You may find yourself buying more than you need. These shops may also have binding calculators, but they will be dependent upon the binding width, so check that too!

I hope this explanation has helped if you are in a bind about backing, batting, and binding measurements.

Happy Quilting!

Laureen

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