Quilt Batting Calculator
Get the right batting size for your quilt top, with the recommended overhang so your batting never falls short while quilting.
Tip: use URL parameters to pre-fill, e.g. ?quiltWidth=72&quiltLength=90.
How the batting calculation works
Batting should always be a little larger than your quilt top. The extra margin, called overhang, gives the quilting needle room to travel and prevents the batting from shifting or pulling out from under the edges while you quilt.
Step 1: add overhang to each dimension. Most quilters use 4 inches per side, which means adding 8 inches to both the width and the length. For a 60" × 80" quilt top, that gives batting of 68" × 88".
Step 2: compare to packaged sizes. Commercial batting is sold in standard sizes such as Crib (45" × 60"), Twin (72" × 90"), Full (81" × 96") and Queen (90" × 108"). If your calculated size fits inside a standard package, that package works — but you'll trim the excess after quilting.
Step 3: buy up, not down. It's always safer to buy batting slightly larger than your calculation. Extra batting is trimmed away; short batting cannot be easily patched without visible seams or weak spots.
If you're sending your quilt to a long-arm quilter, ask about their preferred overhang — many ask for 4 to 8 inches per side so their machine can grab the edges.
What each input means
- Quilt top width and length (inches) — the dimensions of your finished quilt top, measured edge to edge before adding the binding.
- Overhang per side (inches) — the batting margin that extends beyond the top on each side. Four inches is the standard minimum; increase it for long-arm quilting or un-shrunk cotton batting.
The calculator returns the minimum batting rectangle. Since batting is sold in fixed package sizes, your next step is to find the smallest packaged size that fully contains that rectangle, then trim the excess after quilting.
When to use it. Use it when you're ready to buy batting, or when a pattern lists a top size and you want to know which packaged batting size to pick. The calculation is also a useful double-check before you cut: many quilters trim batting to the package size and later discover the margin was smaller than they planned, which leaves no room for the quilt to shift while quilting.
Common mistakes to avoid
- Cutting batting to the exact top size. Batting shifts and draws in while quilting; without margin, you'll have bare spots at the edges.
- Buying a package that "almost" fits. If the calculated batting is 68" × 88", a 72" × 90" package works — but a 60" × 90" one doesn't, even if one dimension fits.
- Forgetting shrinkage. Un-shrunk cotton batting can shrink noticeably in the wash; add an inch or two of overhang or buy pre-washed batting.
- Piecing batting scraps. It's possible with a zigzag or fusible seam, but the join can ridge and show through the quilt. Buying the right size is simpler.
- Ignoring your quilter's requirements. A long-arm quilter's frame needs specific margins; confirm the overhang before you buy.
Frequently asked questions
How much bigger should batting be than the quilt top?
Four inches per side is the standard minimum for home machine quilting. Long-arm quilters often prefer 4–8 inches per side. This calculator defaults to 4 inches but lets you adjust.
Can I piece batting together if it's too small?
You can butt two pieces together with a wide zigzag stitch or a special batting seam, but a visible ridge can form. For best results, buy batting that's already large enough.
Does batting shrink after washing?
Some cotton battings shrink more than others. If your batting is not pre-shrunk, add an extra inch or two of overhang to be safe. Check the manufacturer's label.
Which batting size do I need for a queen quilt?
A queen quilt top is often around 90" × 90". With 4" per side you'd want batting near 98" × 98", so a Queen package (90" × 108") usually works if your quilt isn't wider than 82".