Quilt Backing Calculator

Quilt Backing Yardage Calculator

Calculation Results:

Total Yardage Needed: yards

Total Backing Size Needed: inches

Number of Panels:

*Calculation assumes vertical seams (seams running the length of the quilt) and standard seam allowances.

function calculateBacking() { var width = parseFloat(document.getElementById('quiltWidth').value); var length = parseFloat(document.getElementById('quiltLength').value); var margin = parseFloat(document.getElementById('overhang').value); var fabW = parseFloat(document.getElementById('fabricWidth').value); if (!width || !length || !margin || !fabW) { alert("Please fill in all fields with valid numbers."); return; } var totalWidthNeeded = width + (margin * 2); var totalLengthNeeded = length + (margin * 2); // Logic for vertical panels (standard) var numPanels = Math.ceil(totalWidthNeeded / (fabW – 1)); // -1 inch for selvage/seam var totalInches = numPanels * totalLengthNeeded; var totalYards = Math.ceil((totalInches / 36) * 4) / 4; // Round up to nearest 1/4 yard for safety document.getElementById('yardageOut').innerText = totalYards.toFixed(2); document.getElementById('totalDimsOut').innerText = totalWidthNeeded + '" x ' + totalLengthNeeded + '"'; document.getElementById('panelsOut').innerText = numPanels; document.getElementById('backingResult').style.display = 'block'; }

How to Calculate Quilt Backing Fabric

Choosing the right amount of fabric for your quilt backing is a critical step in finishing your project. If you are sending your quilt to a professional longarm quilter, they typically require an extra 4 to 5 inches of backing and batting on all four sides to properly mount the quilt onto their machine frame.

The Basic Formula

To calculate yardage for standard 42-inch wide fabric, we follow these steps:

1. Add Overhang: Take your quilt top width and length and add 8 inches to each (4 inches per side).
2. Determine Panels: Divide the total width needed by the usable width of your fabric (usually 40-41 inches after removing selvages).
3. Calculate Length: Multiply the number of panels by the total length needed.
4. Convert to Yards: Divide the total inches by 36 to get the yardage.

Standard vs. Wide Back Fabric

Most quilting cotton comes in 42-44″ widths. For a larger quilt (like a Queen or King), you will have to sew multiple panels together to create a piece large enough. Alternatively, "Wide Back" fabrics are available in 108-inch widths, which often allow you to have a seamless backing for even the largest quilts.

Pro Tips for Backing Success

• Square it Up: Always ensure your backing is square. If the backing is wonky, it can cause puckers and pleats during the quilting process.
• Remove Selvages: When sewing panels together, always trim the selvage edges first. Selvages are more tightly woven and can cause the seam to pucker after washing.
• Horizontal vs. Vertical: Think about the direction of your print. If you have a directional fabric, you may need more yardage to ensure the pattern runs the correct way.
• Press Seams Open: For quilt backings, pressing seams open helps reduce bulk, making it easier for the quilting needle to glide through.

Example Calculation

If you have a 60″ x 70″ quilt top and want a 4″ overhang:

• Total dimensions needed: 68″ x 78″.
• Using 42″ fabric (usable 40″): 68 / 40 = 1.7 (Round up to 2 panels).
• 2 panels x 78″ = 156″ total.
• 156 / 36 = 4.33 yards.