Quilt Batting Calculator

How the Batting Calculator Sizes Your Quilt

Batting (also called wadding in the UK) is the middle layer of the quilt sandwich — the insulating fill between the quilt top and the backing fabric. Like backing, batting must extend beyond the quilt top on all sides to allow for quilting movement and final trimming. This calculator adds your specified overhang to the quilt dimensions, compares the result against standard pre-cut batting sizes, and recommends the smallest size that fits.

The standard overhang is 4 inches on each side — the same allowance used for quilt backing. Some quilters use 3 inches for smaller quilts or 6 inches for longarm quilting, where the extra material helps with frame loading. Enter the overhang that matches your quilting setup, and the calculator adjusts accordingly.

After determining the required dimensions, the calculator checks each standard pre-cut size (from crib through king) and flags which ones fit your quilt. If no standard size is large enough, it calculates how much batting to buy by the yard from a bolt, including whether you need to join panels for extra-wide quilts.

Batting Fibre Types Compared

The fibre content of your batting affects the drape, warmth, weight, and quilting behaviour of the finished quilt. The calculator lets you specify the fibre type for your records, though the sizing calculation is the same regardless of fibre. Understanding the differences helps you choose the right batting for your project.

• Cotton batting is the most popular choice for quilting. It has a low loft (thin profile), drapes well, and gives quilts a flat, traditional look. Cotton batting shrinks 3 to 5 percent on the first wash, which creates the slightly crinkled texture many quilters prefer. It must be quilted at intervals of no more than 8 to 10 inches to prevent shifting.
• Polyester batting has a higher loft and does not shrink. It is lightweight, warm, and can be quilted at wider intervals (up to 12 inches). The higher loft gives quilts a puffier appearance. Polyester does not breathe as well as cotton, which makes it less comfortable for bed quilts in warm climates.
• Cotton-polyester blend (80/20) combines the flat drape of cotton with the stability of polyester. Blend batting resists shifting, shrinks less than pure cotton, and can be quilted at wider intervals than cotton alone. This is a good default for quilters who want a traditional look with less fuss.
• Bamboo blend batting is soft, breathable, and drapes beautifully. It has a subtle sheen and is slightly heavier than cotton. Bamboo is a good choice for quilts that will be used as bedspreads where drape matters. It shrinks similarly to cotton.
• Wool batting is the warmest option and has excellent loft recovery — it springs back after compression. Wool breathes well, making it comfortable in both warm and cold weather. It is more expensive than cotton or polyester and requires gentle washing to prevent felting.

For your first quilt, cotton or a cotton-poly blend is the safest starting point. Both are forgiving to work with and available at most quilting shops. The quilt backing and finishing guide includes recommendations for pairing batting types with different quilting styles.

Standard Pre-Cut Batting Sizes

Pre-cut batting packages are sized to match standard bed dimensions plus quilting overhang. Buying a pre-cut package is usually the simplest option — one package, no cutting, no joining. The standard sizes available from most manufacturers are listed here.

• Crib: 45 by 60 inches — fits crib quilts up to about 37 by 52 inches with 4-inch overhang
• Twin: 72 by 90 inches — fits twin quilts up to about 64 by 82 inches
• Full: 81 by 96 inches — fits full or double quilts up to about 73 by 88 inches
• Queen: 90 by 108 inches — fits queen quilts up to about 82 by 100 inches
• King: 120 by 120 inches — fits king quilts up to about 112 by 112 inches

The calculator checks both orientations — a twin package (72 by 90) works whether your quilt is wider or taller, as long as both required dimensions fit within the 72 and 90 inch sides. If your quilt falls between two sizes, the calculator recommends the next size up, because trimming excess batting is easy but adding batting is not.

Buying Batting by the Yard

Pre-cut packages do not cover every situation. Oversized quilts, unusual dimensions, and bulk purchases often make by-the-yard batting more practical. Batting bolts come in standard widths — typically 96, 108, or 120 inches — and you buy whatever length you need.

The calculator finds the narrowest bolt width that covers your required batting width, then reports the length you need in yards. If no standard bolt is wide enough (for quilts requiring more than 120 inches of batting width), the calculator flags that you will need to join batting panels — a straightforward process using a wide zigzag stitch or a hand whipstitch to butt the edges together.

By-the-yard batting is often more economical for large quilts. A king quilt that fits the 120-inch pre-cut might cost less per square inch if you buy from a 120-inch bolt and cut to length. Compare prices at your local shop or online retailer. The binding calculator and border calculator complete the material list for your quilt project.

Preparing Batting Before Quilting

How you handle batting before layering it with the quilt top and backing affects the finished result. These preparation steps apply to all fibre types.

• Unpackage and relax the batting 24 hours before use. Pre-cut batting is folded tightly in the package and develops creases. Lay it flat or drape it over a bed to let the folds relax. A warm dryer cycle (5 to 10 minutes on low heat) speeds this process for cotton and polyester batting.
• Pre-shrink cotton batting if you want a flat finish. Soak the batting in a bathtub of warm water for 15 minutes, then gently squeeze out the excess and lay flat to dry. This removes the 3 to 5 percent shrinkage before quilting, preventing the crinkled post-wash texture. Skip this step if you want the traditional puckered look.
• Do not pre-wash wool or bamboo batting. These fibres can felt or distort when agitated in water before they are quilted. Pre-shrink them only after the quilt sandwich is assembled and quilted.
• Trim batting to size after layering, not before. Lay the batting over the backing (which should be larger than the batting), smooth it flat, then trim the batting to match the backing edges. Cutting to exact size before layering risks the batting shifting during basting.

With your batting prepared, layer it between the backing and quilt top, baste the three layers together, and begin quilting. For general fabric estimation on non-quilting projects, the sewing calculators handle different fabric types and widths.