Quilt batting size calculator
Your batting should be at least 4 inches bigger than your quilt top on every side if it is headed to a longarmer. Enter your quilt size below and we will tell you exactly what you need and which standard package covers it.
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What size batting do I need?
Batting, like backing, needs to be larger than your quilt top so there is something to hold onto during quilting and no risk of the top hanging off the edge. The longarm standard is 4 extra inches per side. If you are quilting on your own machine, 2 to 3 inches per side is plenty, and if you are tying the quilt, you can cut batting close to the finished size.
Batting is sold two ways: precut packages in standard bed sizes, and by the yard off a wide bolt. Packages are usually the better deal, but here is the catch the packaging does not mention: once you add overhang, your quilt often needs the next package size up.
Batting package sizes for common quilts
Standard US package sizes, with the package a longarm-bound quilt actually needs after adding 4" per side. Brands vary by an inch or two, so always check the bag.
| Quilt size | Typical top | Batting needed | Package to buy |
|---|---|---|---|
| Crib | 36" x 52" | 44" x 60" | Crib (45" x 60") |
| Throw | 50" x 65" | 58" x 73" | Twin (72" x 90") |
| Twin | 70" x 90" | 78" x 98" | Queen (90" x 108") |
| Full | 84" x 90" | 92" x 98" | King (120" x 120") |
| Queen | 90" x 95" | 98" x 103" | King (120" x 120") |
| King | 110" x 95" | 118" x 103" | King (120" x 120") |
Yes, you read that right: a twin quilt headed to a longarmer usually needs queen batting, and a full needs king. Skipping the overhang to save a package size is how quilts come back from the longarmer with apologetic notes attached. If you are quilting it yourself with a smaller overhang, set the calculator to 2" or 3" and a smaller package may well fit.
Sources and methodology
Batting needed = quilt width + 2 x overhang, by quilt length + 2 x overhang. The calculator recommends the smallest standard US package whose dimensions cover the needed size, testing each package in both orientations. Package dimensions reflect common US brand standards (Craft 34x45, Crib 45x60, Twin 72x90, Full 81x96, Queen 90x108, King 120x120); individual brands vary slightly. Cross-checked against published quilting references before every update.
Batting questions, answered
Close to it. Many longarmers ask for backing 4" larger per side and are happy with batting the same size or an inch smaller, since the backing is what gets clamped to the frame. When in doubt, cut batting and backing to the same size; nobody has ever been scolded for batting that was slightly too generous.
Absolutely, and thrifty quilters have done it for generations. Butt the two cut edges together (never overlap) and join them with a wide zigzag stitch or fusible batting tape. Once the quilt is quilted, the join disappears. It is a lovely way to use the trimmings this calculator tells you to expect.
Cotton is flat, breathable, and gives the traditional crinkled look after washing; it shrinks about 3 percent. Polyester is loftier, lighter, holds its shape, and resists shrinking, which suits puffy comforter styles. Blends (often 80/20 cotton to poly) split the difference and are the most popular choice for everyday quilts. Size math is the same for all of them.
Generally no. Most modern battings are needle-ready out of the package, and washing unquilted batting can stretch or lump it. If you want to soften the shrinkage of cotton batting, soak it briefly in cool water without agitation and dry flat. Or embrace the shrink: that gentle crinkle after the first wash is half the charm of a cotton quilt.