Quilt Batting Calculator

Batting sold in packages only helps if the package is big enough — and the size printed on the bag is the batting's size, not the quilt it fits. Enter your quilt top's dimensions and this calculator adds the overage, then tells you the smallest pre-cut package that truly covers your quilt.

Batting Calculator

Batting needs the same overage thinking as the back: enter the quilt top size and your allowance per side. Batting and backing are usually bought on the same trip — the backing calculator on the homepage sizes the fabric while this page sizes what goes between the layers.

How it's calculated

Needed size is quilt top + 2 × overage in each dimension. Packages are the standard pre-cut sizes (crib 45 × 60, twin 72 × 90, full 81 × 96, queen 90 × 108, king 120 × 120 in); the calculator checks each in both orientations — batting has no grain direction that matters here — and recommends the smallest that covers your quilt. The bolt alternative assumes the common 90 in wide roll: lengths needed are ⌈need width ÷ 90⌉, each cut to the needed length, and the total is rounded up to the nearest 1/8 yd.

How much bigger than the quilt should batting be?

Batting follows the same rule as backing: it must extend past the quilt top on all four sides, because quilting draws the sandwich in and the edges are only trimmed square at the very end. The standard allowance is 3–4 in per side, matching the backing — and if your quilt is going to a longarm quilter, 4 in per side is usually a requirement, not a suggestion: the frame needs material to grip.

The trap this creates is in the package names. A "twin" package at 72 × 90 in fits a twin quilt of about 64 × 82 in once the overage comes off — not a 70 × 90 in quilt top. Buy by the dimensions you need, which is what the calculator works out, never by the name on the bag.

Choosing a batting fiber and loft

Size is only half the decision. Cotton batting is flat, breathable, and crinkles softly after washing — the classic choice for everyday quilts. Wool is warm, lofty, and shows quilting beautifully, but costs more. Polyester is the lightest and puffiest, dries fast, and suits allergy-prone households; bamboo and cotton-poly blends sit between the extremes.

Loft — the batting's thickness — changes how a quilt drapes and how far apart your quilting lines can be. Every batting states a maximum quilting distance (from 2 in for some cottons to 8–10 in for many polyesters and wool). Whichever package you buy, check that figure against your quilting plan: stitching farther apart than the stated distance lets the batting shift and bunch inside a finished quilt.

How to use this calculator

Add the overage twice to the quilt top's width and length — that is the batting size you need.
Compare against the standard pre-cut packages, in either orientation, and pick the smallest that covers both dimensions.
If no package fits, calculate from a 90 in wide bolt: one length per 90 in of width needed, rounded up to the nearest 1/8 yd.

Worked example

A twin quilt, 70 × 90 in, with the standard 4 in of batting overage per side: the batting must measure 78 × 98 in. A twin package (72 × 90 in) is too small in both directions; a full package (81 × 96 in) is wide enough but 2 in short on length. The smallest package that covers it is the Queen package (90 × 108 in) — trim the excess after quilting. From a 90 in bolt instead: 1 length of 98 in = 2 3/4 yd.

Pre-cut package sizes

Package	Batting size	Fits quilts up to
Crib	45 × 60 in	Quilts up to about 37 × 52 in with 4 in overage
Twin	72 × 90 in	Quilts up to about 64 × 82 in with 4 in overage
Full	81 × 96 in	Quilts up to about 73 × 88 in with 4 in overage
Queen	90 × 108 in	Quilts up to about 82 × 100 in with 4 in overage
King	120 × 120 in	Quilts up to about 112 × 112 in with 4 in overage

Package sizes are The Warm Company's published pre-cut sizes (Warm & Natural and similar lines). Other brands are usually within an inch or two — check the package label.

Related calculators

Backing first: the main backing calculator works out panels and yardage for any fabric width.

Frequently asked questions

Can I join leftover batting pieces instead of buying a package?

Yes — quilters do it constantly. Butt the straight edges together (never overlap, which leaves a ridge) and join with a wide, loose zigzag stitch, or use fusible batting tape. Keep the joined batting the same fiber and loft throughout, and place joins away from the quilt's focal areas.

My quilt falls between two package sizes. Which do I buy?

The larger one, always. The calculator recommends the smallest package that covers your quilt in both dimensions; if that is the next size up from the quilt's name, that is correct, not wasteful — the trim becomes stuffing, practice sandwiches, or the start of a smaller project.

Does batting orientation matter — can I turn a package sideways?

For size purposes, yes, you can: batting has no meaningful grain for quilting, so a package can be turned either way, and the calculator already checks both orientations when it recommends a package. One caution: the size printed on the bag is the batting's size, not the quilt's — with the standard 4 in overage per side, a 90 × 108 package covers quilts up to 82 × 100 in, whichever way it is turned.

Why does the bolt calculation use a 90 in roll?

Batting by the yard is most commonly sold on 90 in wide rolls (some shops stock 96 in or 120 in). If your shop's roll is wider, you may need fewer lengths — divide your needed width by the roll's width and round up to get the length count, then multiply by the needed length.

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