Free tool
Quilt backing calculator
Enter your finished quilt size to calculate how much backing to buy—how many panels you'll piece, which way to run the seam, and whether wide backing saves you money.
Longarm quilters often want 4″ on every side.
Usable width, selvages already removed.
Use the actual shelf or online price.
Editable example price; sales and brands vary.
Still budgeting the entire project? Start with the quilt fabric yardage chart and top estimator, then use this calculator for the backing itself. The wide backing versus standard fabric guide explains the tradeoffs behind the numbers.
How the calculation works
Your backing needs to be bigger than the quilt top—the extra gives a longarm quilter something to clamp, and takes up the shift that happens as the layers are quilted. Four inches on every side is the usual ask, so a 60″ × 80″ quilt needs a 68″ × 88″ backing.
Standard quilting cotton is about 42″ usable once the selvages come off, so any quilt wider than that needs panels seamed together. There are two ways to do it, and they rarely need the same amount of fabric:
- Seams running down the length. Panels sit side by side. Usually better for quilts that are tall and narrow.
- Seams running across. Panels stack top to bottom. Usually better for quilts that are wide and short.
The calculator calculates both and tells you which needs less. It also allows half an inch per seam, which many simplified formulas skip—that can be the difference between a backing that fits and one that's a quarter-inch short on the day.
When wide backing is worth it
108″ wide backing often costs more per yard, but you may buy far less of it. It can cost less overall and eliminate piecing when one continuous piece covers the backing. Oversized quilts may still require two wide panels, so compare the panel count as well as the yardage.
The Utah wide-back fabric directory lists shops with verified 108″ or other wide quilt backing, including options in northern, central, southern, and southeastern Utah. Shops that quilt tops for you are listed separately. Before booking, use the Utah longarm cost calculator and preparation guide to estimate the complete bill and confirm what your quilter expects.
A note on rounding
Results round up to the nearest quarter yard, because that's how fabric is cut. If your number lands right on a boundary, confirm whether cutting tolerance, straightening, or shrinkage justifies buying the next quarter yard.