By Team Quiltdom
Use this free quilt backing calculator to find out exactly how much backing fabric to buy for your quilt. Enter the size of your quilt top, and it tells you the yardage for standard 42 inch quilting cotton or 108 inch wide backing, how many panels to cut, which way the seams should run, and what size batting to buy.
No more standing at the cutting counter doing math on your phone. And no more coming home one panel short.
Backing and Batting Calculator
All measurements in inchesMaking a big quilt? Shop 108 inch wide quilt backing on Amazon
Yardage allows 1 inch for each backing seam (sewn with a 1/2 inch seam allowance) and 2 extra inches on each panel for squaring up, then rounds up to the nearest 1/8 yard. If you prewash, buy a little more for shrinkage.
How To Use The Quilt Backing Calculator
- Measure your quilt top. Lay it flat and measure through the center, side to side for the width and top to bottom for the length. Edges can stretch, so the center is more accurate.
- Choose how much extra backing you need. If a longarm quilter is finishing your quilt, 4 inches on each side is standard, and some ask for more. Check with yours first. If you quilt on a home machine, 2 to 3 inches on each side is usually enough.
- Pick your backing fabric width. Regular quilting cotton is 44 to 45 inches wide, but only about 42 inches is usable once you trim the selvages. Wide backing is 108 inches wide and often lets you skip seams entirely.
- Read your results. The calculator shows the yardage to buy, how many panels to cut, which way to sew them, and the batting size that will fit.
How To Calculate Quilt Backing By Hand
If you want to check the math (or you're at the fabric store without a signal), here is how the calculator works. We'll use a queen quilt top that measures 90 x 108 inches.
- Add the extra to every side. With 4 inches per side, add 8 inches to each measurement. Your backing needs to be 98 x 116 inches.
- Figure out how many panels you need. Divide one side of the backing by the usable fabric width, then round up. For 116 inches, 116 ÷ 42 = 2.8, so you need 3 panels. Each 1/2 inch seam uses 1 inch of width, so three panels cover 124 inches. That's enough for 116.
- Find your cutting length. Each panel must be as long as the other side of the backing (98 inches), plus 2 inches for squaring up. That's 100 inches per panel, and three panels x 100 inches = 300 inches.
- Convert to yards. Divide by 36 and round up to the next 1/8 yard: 300 ÷ 36 = 8.33, so buy 8 3/8 yards.
- Try it the other way. Run the same math turned sideways (panels running the length of the quilt) and pick the smaller answer, unless your print is directional or your longarm quilter wants the seams a certain way. For this queen, the other direction needs 9 7/8 yards, so horizontal seams save you 1 1/2 yards.
The formula: panels = backing side ÷ usable fabric width, rounded up (allow 1 inch per seam). Yardage = panels x (other backing side + 2 inches) ÷ 36, rounded up to the next 1/8 yard.
How Much Backing Fabric Do I Need? (Chart)
Here is a quick backing yardage chart for common quilt sizes, using 42 inches of usable fabric width, 4 inches of extra backing on every side, 1/2 inch seams and 2 inches per panel for squaring up. Your pattern's measurements may be different, so use the calculator above for an exact answer.
| Quilt size | Quilt top | Backing size | 42 in fabric | 108 in wide backing |
|---|---|---|---|---|
| Baby | 36 x 52 in | 44 x 60 in | 2 5/8 yd (2 panels) | 1 3/8 yd |
| Lap | 50 x 60 in | 58 x 68 in | 3 3/8 yd (2 panels) | 1 3/4 yd |
| Twin | 70 x 90 in | 78 x 98 in | 5 5/8 yd (2 panels) | 2 1/4 yd |
| Full | 84 x 96 in | 92 x 104 in | 7 7/8 yd (3 panels) | 2 5/8 yd |
| Queen | 90 x 108 in | 98 x 116 in | 8 3/8 yd (3 panels) | 3 3/8 yd |
| King | 108 x 108 in | 116 x 116 in | 9 7/8 yd (3 panels) | 6 5/8 yd (2 panels) |
Notice the king. With 4 inches on every side, a king backing is wider than 108 inch fabric, so you'd need two wide panels. For a king, compare the cost of 9 7/8 yards of regular cotton against 6 5/8 yards of wide backing.
What Size Batting Do I Need?
Your batting should be about the same size as your backing, so it extends past the quilt top on every side. Batting comes in standard packaged sizes, and it's easy to buy a package that's a few inches too small. Here are the common sizes:
| Batting package | Size | Fits a quilt top up to (4 in extra per side) |
|---|---|---|
| Crib | 45 x 60 in | 37 x 52 in |
| Throw | 60 x 60 in | 52 x 52 in |
| Twin | 72 x 90 in | 64 x 82 in |
| Full | 81 x 96 in | 73 x 88 in |
| Queen | 90 x 108 in | 82 x 100 in |
| King | 120 x 120 in | 112 x 112 in |
Package sizes vary a little by brand. A queen quilt top almost always needs king batting once you add the extra. If you're not sure which batting to choose, read our guide on how to choose quilt batting.
Tips For Piecing Your Quilt Backing
- Trim the selvages first. They're tightly woven and can pucker your seam.
- Use a 1/2 inch seam and press it open. An open seam lies flatter under the quilt. The calculator already allows for it.
- Ask your longarm quilter about seam direction. Many prefer seams that run parallel to the frame's rollers.
- Buy a little extra if you prewash. Cotton can shrink, and narrower fabric can push you into another panel.
- Mark the top edge of directional prints so the backing doesn't end up upside down.
Want something more creative than one fabric? See our quilt back ideas.
Quilt Backing Calculator FAQ
How much backing do I need for a queen size quilt?
For a 90 x 108 inch queen top with 4 inches of extra on each side, you need about 8 3/8 yards of standard 42 inch quilting cotton in 3 panels, or 3 3/8 yards of 108 inch wide backing. That includes 1/2 inch seams and 2 inches per panel for squaring up.
How much bigger should quilt backing be than the quilt top?
For a longarm quilter, add 4 inches on every side (8 inches total to each measurement). For quilting on a home machine, 2 to 3 inches per side is usually enough.
Should quilt backing seams be horizontal or vertical?
Either works. The calculator picks the direction that uses less fabric. If a longarm quilter is finishing your quilt, ask what they prefer.
What is the usable width of quilting fabric?
Most quilting cotton is 44 to 45 inches wide on the bolt. After you trim the selvages, plan on about 42 inches, or about 40 inches if you prewash.
Is 108 inch wide backing worth it?
It costs more per yard, but you buy far fewer yards and skip the seams. Compare the total cost for your quilt size before you decide. The calculator shows both numbers.
Does batting need to be bigger than the quilt top?
Yes. Batting should extend past the quilt top on every side, about the same as your backing, so it doesn't fall short when it shifts during quilting.
How much fabric do I need for quilt binding?
Binding is calculated separately. Our beginner's guide to binding a quilt walks you through it.
Finish Your Quilt With Confidence
Bookmark this quilt backing calculator so it's ready for your next project. Run your numbers before you head to the fabric store, and you'll come home with the right amount the first time.
Planning a new quilt from scratch? Use our quilt size calculator to work out how many blocks you need first.