Quilt Backing Calculator
Calculates how many yards of backing fabric to buy for a quilt, factoring in the overhang needed for longarm quilting or stretching on a frame. Saves trips back to the fabric store.
About this calculator
Quilt backing must be larger than the quilt top on all four sides to allow it to be loaded onto a longarm quilting frame or stretched in a hoop without the edges pulling free. The formula adds the overhang to both ends of each dimension before computing area: total area = (quiltLength + backingOverhang × 2) × (quiltWidth + backingOverhang × 2). That area is then divided by the fabric width to get the required bolt length in inches, and divided by 36 to convert to yards: yardage = [(quiltLength + backingOverhang × 2) × (quiltWidth + backingOverhang × 2)] / fabricWidth / 36. A standard backing overhang is 2–4 inches per side (so 4–8 inches added to each dimension). Note that for large quilts wider than the fabric bolt, you will need to seam backing panels — the calculator gives total fabric needed, and you should plan panel layout separately.
How to use
Your quilt top measures 60" × 80". You want a 3" overhang on each side, and you are using 44"-wide fabric. Step 1 — add overhang: (60 + 6) = 66" wide; (80 + 6) = 86" long. Step 2 — compute area: 66 × 86 = 5,676 sq in. Step 3 — divide by fabric width: 5,676 / 44 = 129 inches of bolt length. Step 4 — convert to yards: 129 / 36 ≈ 3.58 yards. Purchase 3.75 or 4 yards to be safe, and plan to seam two panels since 66" exceeds the 44" bolt width.
Frequently asked questions
How much backing overhang do I need for longarm quilting?
Most longarm quilters require a minimum of 3 to 4 inches of backing extending beyond the quilt top on all four sides, which means 6–8 inches added to both the length and width. This extra fabric is used to clamp or pin the backing to the frame under tension so it lies perfectly flat during quilting. If you are sending your quilt to a professional longarm quilter, ask them for their specific requirements before purchasing backing fabric, as requirements vary by quilter and machine.
Why do I need to seam backing panels for large quilts?
Most quilting cotton is sold at 44" or 45" wide, which is narrower than a typical bed quilt. A queen-size quilt top of around 90" wide, plus backing overhang, requires backing fabric nearly 100" wide — far exceeding a single fabric width. You must cut two or more panels and seam them together, usually with the seam running horizontally or vertically across the quilt back. Wider backing fabric (108" wide, sold specifically as quilt backing) eliminates seaming for most bed quilts.
What is the best fabric to use for quilt backing?
100% quilting cotton is the most popular choice for quilt backing because it is easy to work with, pre-shrinks predictably, and quilts beautifully with both hand and machine stitching. Muslin is an economical option for practice or charity quilts. Flannel makes a wonderfully soft backing for baby and lap quilts. Avoid fabrics that are too thick (like heavy canvas) or too stretchy (like jersey knit), as these make it difficult to maintain even tension during quilting and can distort the finished quilt.