Quilt backing yardage calculator
Enter the finished top size, how much backing overhang your quilter wants, and the fabric width you are buying. The calculator works out the backing footprint, how many panels it takes, what each panel is cut to, and the yardage to buy, then shows the same backing on 108 in wide fabric so you can compare piecing against a single panel.
Both ways of piecing were worked out: panels along the length need 8 3/4 yd, panels along the width need 8 3/8 yd. The buy figure above is the smaller one.
On 108 in wide backing fabric this needs 1 panel and 3 yd, with no piecing at all.
Cutting plan
Bolt view: 42 in usable wide by 300 in long, drawn to scale. Shaded bands are leftover inside the purchased length: 0 sq in (0.00 sq ft). Dashed outlines are segmented strips that get joined end to end.
- Cut a 100 in strip: Backing panel 1 of 3, 42 in long
- Cut a 100 in strip: Backing panel 2 of 3, 42 in long
- Cut a 100 in strip: Backing panel 3 of 3, 42 in long
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The formula, in words
The backing footprint is the top size plus twice the overhang, once on each side. Panels are cut from the usable width (the nominal width minus 2 in). Each join between panels gives up 1 in of cover to its seam allowances, and every panel is cut 2 in long for squaring. The calculator prices both ways of running the panels, along the length and along the width, and recommends the cheaper bolt. Yardage is the bolt length divided by 36, rounded up to the next 1/8 yd.
Worked example
A Queen top at 90 x 95 in with a 4 in overhang needs a 98 x 103 in backing. On 44 in fabric (42 in usable), three panels cover the width. Running the panels along the width cuts each panel at 100 in, a 300 in bolt, so buy 8 3/8 yd. Running them along the length cuts each at 105 in, a 315 in bolt, so that way costs more and the calculator says so. On 108 in backing fabric the whole footprint fits one panel cut at 105 in: buy 3 yd, no seams at all. A King packaged batting at 120 x 120 in is the smallest package that covers the footprint.
Questions quilters ask
How much overhang does a backing need?
Two inches per side is a common home-quilting allowance. Longarm quilters usually ask for 4 in per side, sometimes more, because the backing is loaded on a frame and needs spare fabric at every edge. When in doubt, use your quilter's number, not a chart's.
Why does the calculator subtract 2 in from the fabric width?
Selvages are not usable, and fabric shrinks a little and is rarely cut perfectly straight at the store. Nominal width minus 2 in is the standard planning figure. If you have measured your actual fabric, edit the usable width field and the plan follows your number.
Is wide backing fabric worth it?
For tops wider than about 80 in it usually is: one panel, no piecing seam down the middle, and the yardage often comes out lower than three panels of quilting cotton. The calculator shows both prices in yardage so the comparison is direct.
Which way should the backing seam run?
Either orientation works. Running panels along the width is often cheaper because the panel cut length is the shorter footprint dimension. Avoid a seam landing exactly where the quilt will fold in storage if you can shift it, and keep seams away from the very edge of the quilt.