How To Figure Yardage For Quilt Backing

⚡ Quick Answer: To figure quilt backing yardage, add 8" to both the width and the length of your finished quilt top (4" on each side), then divide the backing width by 40" to find how many widths of fabric you need to piece together. Multiply that number by the backing length, divide by 36, and round up to the nearest ¼ yard. For a 58" × 66" quilt top, that's 4¼ yards of standard 42" fabric — or about 2¼ yards of 108" wide backing with no seams at all.

Once you've pieced your beautiful quilt top, it's time to choose your backing! There are so many fabrics out there, and using 108″ wide backing does make things easier, but we will help you know how much fabric you need when using standard 42" wide fabric.

What You'll Need

• •A pencil and paper (or the calculator above)
• •Your finished quilt top
• •A measuring tape

How to Calculate Quilt Backing Yardage: 4 Steps

Step 1: Measure your finished quilt top. Measure the width and the length of the quilt top after all borders are attached. Measure through the middle rather than along the edges, which can stretch.

Step 2: Add 8" to both measurements. That's 4" extra on each side, top and bottom. This allowance covers the fabric that draws up during quilting and gives a longarm machine enough to clamp onto. If you're sending your quilt out to be quilted, ask your quilter what they prefer — many want 4" to 6" per side.

Step 3: Work out how many widths of fabric you need. Divide your backing width by 40" — the usable width of 42" quilting cotton once the selvages are trimmed — and round up to the next whole number. If the answer is 1, congratulations: your backing fits in a single width and you can simply buy the backing length with no piecing at all. If it's 2 or more, that's how many widths you'll sew together.

Step 4: Turn that into yardage. Multiply the number of widths by your backing length to get total inches, divide by 36, and round up to the nearest ¼ yard. Then cut your fabric to the backing length and piece the lengths together with ½" seam allowances.

Now you are ready to quilt!

A Worked Example

Once borders are added, this finished quilt top measures 58" × 66".

Quilt top width + 8" = backing width: 58" + 8" = 66"

Quilt top length + 8" = backing length: 66" + 8" = 74"

Number of widths of fabric (WOFs): 66" ÷ 40" = 1.65, which rounds up to 2 WOFs

Total inches of fabric: 74" × 2 = 148"

Yardage: 148" ÷ 36" = 4.1, rounded up to the nearest ¼ yard = 4¼ yards

Here's the trick most charts don't mention: you can turn the backing the other way. Instead of two 74" lengths, cut two 66" lengths and run the seam across the quilt instead of down it — that's 132", or 3¾ yards. Same quilt, half a yard less fabric. The calculator at the top of this page compares both orientations for you every time.

Quilt Backing Yardage Chart by Quilt Size

These figures use standard quilt sizes, add 4" of backing on every side, and assume 40" of usable width on 42" cotton, with the seams running the traditional way — parallel to the length of the quilt. Round up if your quilt runs larger or you like a generous margin. The calculator above also checks the crosswise option, so don’t be surprised if it comes back with less yardage than the chart for the same quilt.

Notice what happens at full and queen size: the yardage in standard cotton nearly doubles, because you cross the line into needing a third width of fabric. That's the point where extra-wide backing stops being a luxury and starts being the cheaper option.

Which Way Should the Seams Run?

• •Use crosswise seams for smaller quilts (under about 60" wide). They typically save fabric, and on a throw or crib quilt nobody notices the seam direction.
• •Use lengthwise seams for larger quilts. On a bed quilt, a seam running the length of the quilt sits along the mattress rather than across the sleeper, and it wears better over years of washing.
• •Let the print decide if it's directional. A stripe, a border print, or anything with an obvious top and bottom overrides the fabric math — run the seams whichever way keeps the print upright.
• •Center your seam, or don't. Two full widths give you a seam straight down the middle. If you'd rather avoid that, split one width in half and sew a panel to each side of a full center width instead.

Tips and Tricks for Backing

• •Measure your quilt top vertically and horizontally, and add 8" to both so you have 4" all the way around for the fabric taken up in quilting and for the quilting frame.
• •Trim off all selvages and use a ½" seam allowance when piecing the backing. Sew the pieces together along the longest edge and press the seam allowance open to decrease bulk.
• •Don't hesitate to cut a length of fabric in half along the fold line if it saves fabric and makes the quilt easier to handle. Large quilts might require 3 lengths.
• •Choose a backing layout that suits your quilt — think about the direction of the pattern and pattern matching before you cut.
• •Buy your backing at the same time as your quilt top fabric if you can. Bolts sell out, and dye lots shift.
• •A busy print hides quilting stitches and the odd wobble; a solid or a tone-on-tone shows every stitch. Choose based on how confident you feel about the quilting.

Wide fabrics make backing a quilt seamless. Visit our wide backing fabrics to find your next quilt's back!

Frequently Asked Questions

How much backing fabric do I need for a queen size quilt?

A queen quilt top around 90" × 95" needs a backing about 98" × 103" once you add 4" all the way around. In standard 42" quilting cotton that's three widths pieced together, or about 8¼ yards. In 108" wide backing it's a single seamless cut of about 3 yards — which is why most quilters switch to wide backing at queen size.

How much extra backing fabric do I need beyond the quilt top?

Add 4" on every side, so 8" total to both the width and the length. That extra allows for the fabric that draws up during quilting and gives a longarm machine something to grip. If you're sending your quilt to a longarm quilter, ask what they prefer — many request 4" to 6" per side.

What is the usable width of 42-inch quilting cotton?

Quilting cotton is sold as 42" to 44" wide, but you lose the selvages and a little to squaring up, so figure 40" of usable width. That's the number to divide by when you're working out how many widths of fabric you need.

Do I need to prewash backing fabric?

It's a personal choice, but if you prewash your quilt top you should prewash your backing too so the two shrink at the same rate. If you prewash, buy about 5% extra to cover shrinkage — the calculator above has a checkbox for this.

Should the backing seam run horizontally or vertically?

Whichever direction uses less fabric, unless the print is directional. Turning the backing so the seams run crosswise often saves a half yard or more on smaller quilts. For quilts over about 60" wide, vertical seams usually hang and wear better on a bed.

What seam allowance should I use to piece a quilt backing?

Use a ½" seam allowance rather than the ¼" you use for piecing blocks — backing seams take a lot of stress during quilting. Trim off the selvages first, because they're tightly woven and will pucker. Press the seam open to reduce bulk under the quilting.

Is 108-inch wide backing worth it?

For anything from a twin up, usually yes. You get a seamless back, you skip the piecing entirely, and once you account for the yardage you'd waste piecing three widths together, the cost often comes out close to even. For small projects like crib quilts and table runners, standard 42" cotton is still the more economical choice.

More Backing Help

• Wide Quilt Backing 101: Your Complete Guide — how to choose the right backing fabric, avoid common mistakes, and get a professional finish
• Quilt Sizes Chart — every standard quilt measurement from crib to California king
• How to Baste a Quilt — Spray, Pin & Board Methods Compared — the next step once your backing is pieced
• Best Batting for Machine Quilting — what goes between your top and your backing
• Pressing Seams: Open vs. to the Side — including why backing seams get pressed open
• The Complete Quilt Binding Guide — finish the edges once the quilting is done