How to calculate batting size
Batting size = quilt top + 2 × extra (on width and on length)
Batting needs the same margin as the backing: the quilting draws the layers in, and a longarm frame needs something to hold. 4" on each side is standard for longarm quilting; 2–3" is usually enough if you quilt it yourself.
Worked example: 60" × 72" quilt
With 4" on each side you need batting at least 68" × 80". A twin package (72" × 90") fits. From a 90" roll, buy 68": 2 yards.
Common batting package sizes
Sizes vary slightly by brand, so check the label.
| Package | Typical size |
|---|---|
| Crib | 45" × 60" |
| Twin | 72" × 90" |
| Full | 81" × 96" |
| Queen | 90" × 108" |
| King | 120" × 120" |
Buying batting by the yard
Batting on the roll usually comes 90", 96", 108" or 120" wide. If one side of your batting fits within the roll width, you only buy the other side's length. The calculator shows the narrowest roll that works.
Joining leftover batting
To use up scraps, trim two pieces with straight edges, butt them together without overlapping, and join them with a wide zigzag stitch or fusible batting tape. Keep joins away from the edges of the quilt.