Quilt Backing Calculator – How Much Fabric Do You Need?🧵 QuiltBacking
🧵 Quilt Backing Calculator
Quilt Backing Calculator
Enter your quilt dimensions and get exact yardage, seam placement, and panel cutting instructions for your backing fabric.
🧵 Quilt Backing Calculator
Extra beyond quilt edge (2–6 inches typical)
BACKING FABRIC NEEDED
–Yards
–Metres
–Panels
–Total Inches
Quilt finished size–
Backing size needed (with overhang)–
Fabric width (usable after wash)–
Number of panels to cut–
Length of each panel to cut–
Seam allowance (each seam)–
Total fabric to purchase–
Quilt Backing Guide
Calculating quilt backing fabric is one of those tasks that seems simple but trips up quilters of every experience level. Buy too little and you face a frustrating mid-project trip to the fabric shop — and your dye lot may no longer be available. Buy too much and you waste money. The quilt backing calculator above eliminates both problems by accounting for your specific quilt dimensions, chosen fabric width, and seam allowances.
Standard Quilt Sizes & Approximate Backing Needs
Quilt Size
Finished Dimensions
Backing (42″ fabric)
Backing (60″ fabric)
Baby/Lap
36″ × 45″
2.5 yards
1.5 yards
Throw
50″ × 65″
4.0 yards
2.25 yards
Twin
60″ × 80″
5.0 yards
2.75 yards
Full/Double
75″ × 87″
6.5 yards
5.5 yards
Queen
90″ × 108″
8.5 yards
7.0 yards
King
108″ × 108″
10.5 yards
8.5 yards
🧵 Pro Tip: Always pre-wash your backing fabric before cutting. Cotton shrinks 2–5% after washing. Pre-washing also removes sizing and makes the fabric easier to quilt through. Add an extra 4–6 inches to your backing dimensions before washing to account for shrinkage.
Your quilt backing should extend 2–4 inches beyond each edge of the quilt top (4–8 inches total per dimension). For longarm quilting, many longramers require 4–6 inches of overhang on all sides. The quilt backing calculator above uses 4″ overhang per side as the default, which you can adjust.
Whether you need to piece the backing depends on your quilt width relative to fabric width. If your backing needs (quilt width + overhang) exceed the usable fabric width, you’ll need to cut multiple panels and sew them together. For large quilts, using extra-wide backing fabric (108″) eliminates seaming entirely and saves significant time.
Avoid placing a seam in the centre of a 2-panel backing — a centre seam sits on the most-used part of the quilt. Instead, cut one panel in half lengthwise and sew one half-panel to each side of the full-width panel. This creates two seams offset from centre, distributing wear more evenly and looking more professional.