Calculating fabric for a quilt back

    Quilters will often come into the store asking for help to calculate yardage for a quilt back. We love to help but that is often a loaded question. It depends on how you intend to construct or piece your back. There are multiple ways to do this and none are more right or wrong than the other.

    It is important to note in all cases that you should measure the center length and center width of your quilt top to determine the actual length and width.

    Sometimes you want to piece the back with lengthwise seams. In this case you would buy the yardage the length of your quilt. You may have to double or triple the yardage if the quilt is wider than 40 inches or 80 inches.

    Other times it is more efficient to piece the back crosswise. In this case you would buy the yardage the width of your quilt and double or triple the measurement if the length is longer than 40 or 80 inches.

    I've become a big fan of piecing my backs from scraps. I get two quilts in one this way. So I would determine yardage based on the quilt pattern. I always design the border to accommodate the fact it's going to be lopped off after quilting.

    You can get similiar dual purpose out of your backs using cheater fabrics and crosswise and lengthwise seams. Some great "cheater" fabrics at Wish right now are Winter Log Cabin (in the sale room!), and In Love With Nature's Pinwheels by Susan Branch. I used the Winter Log cabin on the back of Cheery Cherry Pie, the Sew Sweet Shop Scrap club sample quilt hanging in the front of the store.

    Another, less known way, of piecing a back is John Flynn's biased seam method. It's a very smart technique. If you are going to put your quilt on a frame this is the best way to distribute the back seam. It's also the most effiecent use of yardage. John has posted his method on his website. If memory serves me correctly he has a great demonstration on how to fold and cut that long bias edge with your 6 inch by 24 inch ruler on his instruction video that he packs with his frame. The basic formula is:

    Length of fabric to buy = length of quilt top + length of quilt top( width of quilt top - width of fabric)/ 2 x width of fabric - width of quilt top

    For those who get confused by equations:

    Record the width and length of your quilt top (add any desired overhanging for the back to these measurements before you begin any other calculations). Record the width of the fabric you are considering (usually 40-44 inches. I'd recommend using 40 if you are unsure).

    Multiply 2 times the width of the fabric you are considering (if you are using the safe bet of 40 then this will always be 80 inches). Subtract the recorded width of the quilt top. Save this first number.

    Take the recorded width of the quilt and subtract the width of the fabric being considered (40). Multiply by the recorded length of the quilt. Add the recorded length of the quilt. Now divide by the first saved number.

    Voila! You have the recomended length of fabric in inches. Divide by 36 if you want yards.

    Or you can just come into Wish and we'll put two heads on the calculations and help you out. ;)

    Do you have another method of calculating yardage for a quilt back?

    14 thoughts on “Calculating fabric for a quilt back”

    • [...] Wish Upon a Quilt blog has some great advice about calculating yardage for a quilt back. See the post. [...]

    • Beth

      I don't have another method for calculating fabric for a quilt back, but I do have an additional step I always follow. When I'm using a lengthwise seam for the quilt back that is under 80 inches wide, I determine how much additional width is needed and add an additional 1/2 inch.

      I then sew the second piece to the first, lengthwise, and then sew the other unfinished edges together. This results in a "tube". I fold the tube so that the seams match, then slice the backing along the center of the smaller side. The end result is a quilt back with two seams, with the center perfectly centered. The instructions make it sound like more work than it is.

    • Judy Currie

      I have great success with the 108" backs - if they have a color that will work. Other than that I generally piece the backs or just add a coordinating strip to make it wider. Judy C wants to win the free fabric

    • Cecilia Young

      Thank you for your instructions on backing material. I seem to have a hard time figuring out how much fabric I need. But then again, I am just a beginner. Hopefully, with time I will learn. :) Plus, I always love getting fabric.

    • Winnie McCrary

      I like the 108" backs too. However, I have found the the Fabric Calculator works well for me when I have to by standard width yardage.

    • Sue Fahey

      Thanks for making the calculations so easy. I, too, would like the fabric...yum, yum. Sue

    • Diane Davis

      This is a great article! I tend to use my FabriCalc now since I had such a hard time remembering how to figure out how much to buy. I like to do the seams on the sides with a center panel because I think the center gets the most wear if it's a well used quilt.

      The article is a definate "keeper" and has found a permenant spot in my quilting project book. Thanks :)

    • Jeanne

      I definitely prefer the wide backing. It is more economical and you have fewer seams to worry about. However, I did make a quilt for my granddaughter that had a pieced back--really two quilts in one and truly a "labor of love"!

    • Carol Broughton
      Carol Broughton March 12, 2009 at 5:38 pm

      Thank you for the helpful info - this is always where I ask for help or just get way too much fabric. Love the blog!

    • Shelley C

      I have a housefull of grandkids at the moment and no time to read much, but I will be back to read this article. Any help i can get with estimating yardage etc is soo helpful! Thanks for making this available to all.

    • wendy

      Very good comments! I love the discourse. For those who don't have a FabriCalculator check out the online Quilt Calculator at It is fabulous. I would use this in addition with EQ to plan BOM's for my Virginia guild. The calculator does most quilting shapes and will tell you how many strips to cut, how much fabric you will need, cutting dimensions, and how many extra pieces you will have when you input the finished size and number of pieces desired. It will calculate squares, rectangles, triangles, trapezoids, quilt backs, and sashing! And it seems to work on Web Enabled phones. (You just have to be patient with the connection speed- it's better than most web sites.)

    • Anne

      I'm fascinated by the mentioned John Flynn method and I think I will give it a try this weekend. The timing is perfect as I am about start putting together a pioneer block quilt. I'm also a fan of 108" backings, but sometimes there are certain fabrics I'd just love to have for a backing. Great blog and information~ thanks!

    • Jane Goetz

      The store carries two fabulous extra wide batik fabrics for backing, plus five other colors. It's great not to have to piece a round or large quilt. The quality is also great-not thin and limp.

    • Sherry Hogan

      I need to make a bias strip 24 inches long for a basket handle and it is suppose to 1 1/2 inches wide I have no idea how much fabric I need to make this without having a seem.

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