how to calculate how much binding tape to make
Looking for how to make your binding tape, how to attach your binding, or how to finish sewing your binding on? You can find those posts here:
For those non-quilters or beginning quilters (or those simply in need of a refresher), let’s start with the basics: binding is the final step of construction to making a quilt. It’s the way we “finish the edges” of our quilt sandwich, so they aren’t open to getting snagged on things, or stuff getting in between the layers of the quilt. I like to think of the binding as the “frame” of the quilt. And just like with framing, there are a myriad of options from an aesthetic standpoint, but they all function the same way.
Quilts are often bound with what’s called double fold binding tape (and by tape, I mean, fabric tape). The tape starts out as a strip of fabric and is folded once, wrong sides together, then attached to the quilt. Then it is folded a second time over and around to the other side of the quilt. Double fold binding tape is extremely tough: because there are two layers of fabric to it, it really protects the borders of your quilt!
When I bind my quilts, I typically use Crossgrain Double Fold Binding Tape (scroll to the end of the post to read more about Crossgrain vs Bias tape). Before I start making my tape, I need to figure out a couple things:
How wide my tape will be
How much tape I need to make
How many width-of-fabric (WOF) strips I need to cut
Let’s take a moment to go through each of these steps.
Width of Tape
When I say “width of tape,” I’m referring to the starting width of the fabric strips, not the finished border. I almost always cut my strips to 2½” wide. I might use a 2¼” width instead if I’m working with a thinner batting and a lightweight binding fabric (like a cotton lawn). Either of these generally give a nice border to the front without having to struggle to make it around to the back to affix it.
Now you might be thinking that a ¼” doesn’t make a ton of difference, but when it comes to binding tape it does. Because, not only is a half inch eaten up when you attach the binding to the quilt, but then you’ve got to have enough to wrap around the quilt sandwich and then the stitches on the back.
I’ve gotten into trouble on a couple quilts with a 2¼” binding tape that just barely made it over and around to cover the stitches on the back. I should’ve just redone the binding, because I wouldn’t be surprised if the binding stitches pop once I start using the quilt.
So, if you’re debating between different widths and unsure if it’ll work, try using a couple scraps of fabric to model it out before you commit to a width.
How Much Tape & Fabric Do I Need? (aka The Math)
Figuring out how much binding you’ll need is easy: add the width and length of your quilt, multiply it by two, then add 10 to ensure that you’ll have enough length to join the ends together.
Length of Tape = (Width of Quilt + Length of Quilt) x 2 + 10
One you have the length of binding tape you’ll need, divide it by your WOF measurement minus 2, and round up to the next whole number to get the number of strips you’ll need to cut. Why minus 2? I always err on the side of caution and factor in a couple inches on each strip to account for fabric that gets “eaten” when constructing the tape.
Number of Strips (rounded up) = Length of Tape / (Width of Fabric - 2)
To figure out how much yardage you need, take the width of your binding strips and multiply it by the number of WOF strips you’ll need, divide that number by 36 and round up to the nearest fraction of a yard that your local quilt shop cuts to (for some folks, that’s an eighth, a quarter, or a third).
Yardage (round up to nearest fraction) = (Number of Strips) * (Width of Tape) / 36
A Note About Bias vs Crossgrain Binding Tape
All the math above is for making crossgrain tape, but you might have also heard the term “bias” tape thrown around. When making binding tape, there are two main ways to cut it: first is on the bias and second is cross-grain. Let’s talk about bias and grain for a second because this is an important distinction and decision to make when you’re binding. If you’re a garment sewist, this is probably going to be old hat for you since grain is illustrated on patterns and you can’t escape it!
If you take a giant step back and think of a loom, you’ve got two directions of fibers being woven perpendicular to each other. Those that are perpendicular to the selvage are called “Crosswise” (my blue tape here) and those that are parallel to the selvage are called “lengthwise gain” (my green tape here). Which makes sense when you think of fabric being unwound from a bolt: the selvage is running along the length, so the fibers running parallel to that create the lengthwise grain. And the “Cross grain” is running the width across the loom (that’s how I remember it).
The bias runs diagonally across the fabric grain, making it extremely stretchy. The easiest way to see how different the stretch is, is to take a scrap of fabric and pull on it. Lengthwise has very little stretch, Crosswise has a little bit more stretch, and Bias has a ton of stretch!
Keeping that flexibility in mind, let’s get back to binding tape: for quilts that are square or rectangular in shape, having a ton of stretch in your binding isn’t as important: you can safely cut your binding strips along the crosswise grain, aka you can cut “Width of Fabric” strips and join them up to make your tape.
Now, if you’re working with a quilt that has rounded edges, think of a classic wedding ring quilt or if you’re making a quilt coat with curved edges, then you’re going to want to have some give to your binding to flow with the curves. This is where bias tape comes in super handy as it gives and stretches beautifully.
What’s Next?
Making bias binding tape takes longer than making crossgrain tape and since my quilts typically have 90 degree corners, I almost always opt to make crossgrain binding tape. So, once you’ve figured out how much tape you’ll need, read on to learn how to make your tape!