Quilt Backing Fabric Calculator
Use this calculator to determine how much fabric you'll need for your quilt backing, considering your quilt top dimensions, backing fabric width, and desired margins.
Common widths: 44/45″, 60″, 90″, 108″
Recommended 2-3 inches per side for quilting and squaring up.
This is the amount lost per seam when joining backing panels.
Results:
Enter your quilt dimensions and fabric details to calculate the required backing fabric.
Understanding Quilt Backing Fabric Needs
The backing of your quilt is just as important as the top. It provides stability, adds to the overall aesthetic, and is crucial for the quilting process. Calculating the correct amount of backing fabric is essential to avoid running out mid-project or wasting precious fabric.
Why Calculate Your Backing Fabric?
- Prevent Shortages: Running out of fabric when you're ready to quilt can be frustrating and delay your project.
- Minimize Waste: Buying too much fabric is costly and leaves you with unnecessary scraps.
- Ensure Proper Fit: A backing that is too small can lead to puckering, distortion, or difficulty loading onto a longarm machine.
- Plan for Seams: Knowing if you'll need to piece your backing allows you to plan your fabric cuts and seam placement effectively.
Key Factors in Backing Fabric Calculation
Several variables influence how much backing fabric you'll need:
- Quilt Top Dimensions: The finished width and length of your quilt top are the starting point.
- Backing Fabric Width: Standard quilting cotton typically comes in 44/45-inch widths. However, wider fabrics (e.g., 60″, 90″, 108″) are available, often called "wideback" fabrics, which can eliminate the need for piecing.
- Extra Margin: It's crucial to add extra fabric beyond the quilt top's dimensions. This margin (typically 2-4 inches on each side, so 4-8 inches total for both width and length) provides room for:
- Squaring up the quilt after quilting.
- Loading onto a longarm quilting machine.
- Potential fabric shrinkage during washing.
- "Draw-up" from the quilting stitches.
- Seam Allowance for Joining Panels: If your backing fabric isn't wide enough to cover your quilt top in a single piece, you'll need to join multiple panels. Each seam will consume a small amount of fabric (e.g., 0.5 inches per seam). This calculator accounts for that loss.
Understanding Fabric Orientation and Seams
When piecing backing fabric, you generally have two options for seam orientation:
- Vertical Seams: The panels run parallel to the length of your quilt. This is often preferred as it creates fewer seams across the width of the quilt, which can be easier to manage during quilting.
- Horizontal Seams: The panels run parallel to the width of your quilt. This might be more efficient for certain quilt dimensions or fabric widths.
Our calculator will suggest the most fabric-efficient orientation for your specific project.
Using the Quilt Backing Fabric Calculator
Simply input the following details:
- Quilt Top Width (inches): The measurement of your finished quilt top from side to side.
- Quilt Top Length (inches): The measurement of your finished quilt top from top to bottom.
- Backing Fabric Width (inches): The width of the fabric you plan to use for your backing (e.g., 44, 60, 90, 108).
- Extra Margin (inches per side): The additional fabric you want to add around your quilt top for ease of quilting and squaring up.
- Seam Allowance for Joining Panels (inches): The amount of fabric you'll lose in each seam if you need to piece your backing. A standard 1/2 inch (0.5) is common.
The calculator will then provide you with the required backing dimensions, the number of panels needed, the length to cut each panel, and the total fabric required in both inches and yards, along with an orientation suggestion.
Examples:
Example 1: Twin Size Quilt with Standard Fabric
- Quilt Top Width: 60 inches
- Quilt Top Length: 80 inches
- Backing Fabric Width: 44 inches
- Extra Margin: 2 inches per side
- Seam Allowance: 0.5 inches
- Result: You'll likely need two panels, each cut to approximately 64 inches, totaling around 3.6 yards of fabric. This uses horizontal seams for efficiency.
Example 2: Queen Size Quilt with Standard Fabric
- Quilt Top Width: 90 inches
- Quilt Top Length: 100 inches
- Backing Fabric Width: 44 inches
- Extra Margin: 2 inches per side
- Seam Allowance: 0.5 inches
- Result: This will require three panels, each cut to approximately 94 inches, totaling around 7.9 yards of fabric. This uses horizontal seams for efficiency.
Example 3: Queen Size Quilt with Wideback Fabric
- Quilt Top Width: 90 inches
- Quilt Top Length: 100 inches
- Backing Fabric Width: 108 inches
- Extra Margin: 2 inches per side
- Seam Allowance: 0.5 inches (though not used if no seams)
- Result: With 108″ wideback, you'll only need one panel, cut to approximately 94 inches, totaling around 2.75 yards of fabric. No seams needed!
Tips for Buying Backing Fabric
- Round Up: Always round up to the nearest quarter or half yard when purchasing fabric to account for slight inaccuracies in cutting or potential shrinkage.
- Pre-wash (Optional): If you pre-wash your quilt top fabrics, consider pre-washing your backing fabric as well to prevent differential shrinkage.
- Directional Prints: If your backing fabric has a directional print, ensure you account for this when planning your cuts and seams.
- Consider Design: The backing is part of the quilt's design! Choose a fabric that complements your quilt top.
Required Backing Dimensions:" +
" Width: " + requiredBackingWidth.toFixed(1) + " inches" +
" Length: " + requiredBackingLength.toFixed(1) + " inches
" +
"Number of Panels Needed: " + finalNumPanels + "
" +
"Length to Cut Each Panel: " + finalLengthPerPanel.toFixed(1) + " inches
" +
"Suggested Orientation: " + finalOrientationText + "
" +
"Total Fabric Needed:" +
" " + finalTotalFabricInches.toFixed(1) + " inches" +
" " + displayYards.toFixed(1) + " yards (approx.)
" +
"Recommendation: Purchase at least " + purchaseYards.toFixed(2) + " yards to allow for squaring up and minor adjustments.";
}
// Run calculation on page load with default values
window.onload = calculateQuiltBacking;