Using 108″ wide-back fabric is a dream for quilters because it often eliminates the need for bulky seams on the back of your quilt. To find out how much you need, follow this simple process:
Step 1: Determine the Final Backing Size
A quilt backing must always be larger than the quilt top to account for "draw-in" and the requirements of longarm machines. Most quilters add 4 inches per side (8 inches total to both width and length).
Step 2: Compare Against the 108″ Width
Because the fabric is already 108 inches wide, we check if either your width or length fits within that 108-inch limit. For example, if your quilt is 80″ x 90″, and you add 4″ margins, the backing needs to be 88″ x 98″. Since both 88 and 98 are less than 108, you can choose the most efficient direction to cut the fabric.
Step 3: Convert to Yardage
Once you know the dimension that isn't running along the 108″ width, you divide that number by 36 to get the total yards required. We always recommend rounding up to the nearest 1/4 yard to account for squaring up the fabric.
Example Calculation:
Quilt Top: 60″ x 70″
Plus 4″ Margin: 68″ x 78″
Orientation: We use the 108″ width to cover the 68″ side.
Need: 78 inches of fabric length.
Math: 78 / 36 = 2.16 yards.
Final Answer: Buy 2.25 yards (2 1/4 yards).
Benefits of Using 108-Inch Wide Fabric
No Seams: Avoid the extra thickness and work of sewing two pieces of 44″ fabric together.
Cost Effective: While 108″ fabric costs more per yard, you usually buy less total yardage compared to pieced 44″ fabric.
Time-Saving: Simply square up the ends and your backing is ready for the frame.
function calculateBacking() {
var width = parseFloat(document.getElementById('quiltWidth').value);
var length = parseFloat(document.getElementById('quiltLength').value);
var margin = parseFloat(document.getElementById('marginAmount').value);
var resultDiv = document.getElementById('backingResult');
var output = document.getElementById('resultOutput');
if (isNaN(width) || isNaN(length) || isNaN(margin)) {
alert("Please enter valid numbers for all fields.");
return;
}
var totalW = width + (margin * 2);
var totalL = length + (margin * 2);
var fabricWidth = 108;
var yardage = 0;
var inches = 0;
var note = "";
// Check if the quilt is too big even for 108″ fabric without piecing
if (totalW > fabricWidth && totalL > fabricWidth) {
output.innerHTML = "Note: This quilt is too large for a single piece of 108\" fabric. Your required dimensions are " + totalW + "\" x " + totalL + "\". You will need to piece your 108\" backing, or use a wider margin.";
resultDiv.style.display = 'block';
return;
}
// Calculate most efficient yardage
// If both fit, take the smaller dimension as the one to cut (to save money)
if (totalW <= fabricWidth && totalL <= fabricWidth) {
var sideToCut = Math.min(totalW, totalL);
// However, usually we orient length for length, let's pick the smaller one to minimize waste
inches = Math.min(totalW, totalL);
note = "Since your quilt fits both ways, we used the smaller dimension to calculate yardage to save you money.";
} else if (totalW <= fabricWidth) {
inches = totalL;
note = "Your quilt width fits within the 108\" fabric width. You need " + totalL + "\" in length.";
} else {
inches = totalW;
note = "Your quilt length fits within the 108\" fabric width. You need " + totalW + "\" in length (rotated).";
}
yardage = (inches / 36).toFixed(2);
var suggestedYardage = (Math.ceil(yardage * 4) / 4).toFixed(2); // Round up to nearest 0.25
output.innerHTML = "Required Backing Dimensions: " + totalW + "\" x " + totalL + "\"" +
"Exact Yardage: " + yardage + " yards" +
"Suggested Purchase:" + suggestedYardage + " yards (" + inches + " linear inches)" +
"" + note + "";
resultDiv.style.display = 'block';
}