Figuring Yardage for Quilt Backs

Having been a quilt store owner in the past, one of the most common questions I was asked was how many yards of fabric do I need for this quilt? And you can start just by measuring your quilt. But I have some generalities here also. The equation for figuring out how big to make a quilt for a particular size of bed is helpful information that leads to how much yardage you're gonna need for your backing. So that general equation is simply the mattress size plus the width of the drop times two plus some excess for quilting. Now, what is the drop? The drop is that which comes off the edge of the quilt. The top of the quilt has a certain measurement. So for a king size, the mattress is 76 inches by 80 inches. For a queen size, the mattress is 60 by 80. For a full size, it's 54 by 74. For a twin, for an average throw and an average baby, I have those sizes marked here too. Then I did the math for you, but I want you to understand the math 'cause my doing it for you doesn't help you if your quilt has a different size. So how big do I need to make my queen size quilt? Well, I need to start with that 60 by 80, that's the portion that's on the top of the mattress. Then the drop is that portion that hangs down or usually that is the borders or the border system. It could be one border, all one border. It could be two or three borders. But that border is the drop. And you're gonna have that twice, one on each side. One on the top one on the bottom. So if I have a king size quilt and my mattress is 76 by 80 and I want a 14 inch drop because I've got an extra deep mattress, then 14 times two is 28 and I need to add 28 to 76 which yields 104 and 28 to 80 which yields one 108. So my quilt is probably gonna be somewhere around 104 inches by 108 inches for a king. Some people just make it 108 inches square. But then I need excess backing. I can't have just that amount of backing. If I'm gonna send it to a long arm quilter they want 12 extra inches total, six inches on every side. They need this to get it into their machine the way they need it in their machine. If you're quilting on your own, either by hand or by your home machine or on any machine where you're not loading it into a frame, then you only need about six inches of excess, three on all sides. Three inches on one side, three inches on the other, three inches on the top and on the bottom. So you need to add that into your measurement. So for long-arm quilting that's gonna take our king size backing from 104 by 108 to 116 by 120. Or if we're quilting it at home to 110 by 114. So now have the size of our quilt top. If we already have our quilt top made we can simply measure it. But a lot of times we're buying our backing fabrics as general ideas because we're buying them when they're on sale. I see this beautiful fabric, it's half price, it looks like there's a lot of yardage on the bolt still, maybe I can buy a quilt back. Because for the average king size quilt I need nine and a quarter yards. That's a lot of yardage. For the average queen size quilt, I need seven and seven eighths yards. For the average full-size quilt, I need seven yards. And so on. How we figure this is we look and we say if our piece is 104 by 108, how many widths of fabric do I need? A width of fabric is how wide the fabric is with the selvages removed. So a fabrics at the store, anywhere from these days 40 to 42 and a half, maybe 43 inches. They used to be up to 44 inches but I haven't seen one of those in a long time. And then we have to either rip off or cut off the salvagers because the salvage had been pulled tight and they cause puckering. So those need to be removed. So generally speaking, we can say that we have 40 usable inches. So every 40 inches is one width of fabric. So I generally take my smaller measurement and divide it by that 40. So how many times will 40 go into 104? It's gonna take three times. That would be 120 inches. So I'm gonna have to have three widths. And each of those widths needs to be 108 inches long, or 120 inches long, I'm sorry. So I'm gonna multiply 120 times three because that's how many widths I need. And then I'm gonna divide that by the yard, which is 36 inches divided by 36 inches. And that gave me nine and a quarter yard. So that is how you figure out how much yardage you need. First you determine how many widths, 40 inch width you need, then the length, and you multiply that length by how many widths you need, and then you divide it by the 36 inches in a yard. So I'm gonna do another size for you real quick. So let's talk about a twin. And our twin, say our twin ends up needing to be 75 inches by 110. Well, 75 divided by 40, I only need two widths, which is quite nice, just two widths because I can get 80 inches when I sew that together. So, but I need those two widths to each be 110 inches long. So that's 220 inches. When I divide that by 36, I end up getting five and seven eights yard that I need for the backing of an extra long twin. So that's how you figure out your quilt backing. It's pretty simple. It is some math though, but I know you can figure it out. If not, you can use my cheat sheet.