Quilt backing: panels, seams and overage
A backing is bigger than the quilt top. One shop's guide adds four inches on every side; guides written for longarm quilting ask for five. The backing width is the top plus the extra twice, and so is the length.
Fabric is bought by length, and its width is fixed. Quilting cotton sold as forty-two to forty-four inches wide gives about forty inches once the selvages are cut off, and one guide insists on dividing by forty for that reason. When the backing is wider than the fabric it is pieced from panels sewn side by side, and each seam takes a seam allowance from both panels. The number of panels is the smallest number whose widths, less the seams, cover the backing.
The panels can run either way. With the seams along the length of the quilt, each panel is as long as the backing and enough of them are needed to cover its width. With the seams across, each panel is as long as the backing is wide and enough are needed to cover its length. The two totals are often different: in the guide's own example, a top of fifty-eight by sixty-six inches takes a hundred and forty-eight inches one way and a hundred and thirty-two the other. The calculator works out both and, unless you choose, takes the shorter.
Wide backing fabric, sold at about a hundred and eight inches, usually needs no seam, and then the amount is simply the shorter side of the backing that still fits across the fabric. The exact length is rounded up to the step the shop cuts in.
Chart: backing fabric to buy on standard quilting cotton, by quilt length and width
Each cell is the backing to buy for the quilt length in its row and the width in its column, with four inches extra on each side, forty inches of usable width, half-inch seams and whichever seam direction needs less, rounded up to a quarter yard.
| Quilt top width | |||||||
|---|---|---|---|---|---|---|---|
| Quilt top length | 40 in | 50 in | 60 in | 70 in | 80 in | 90 in | 100 in |
| 50 in | 2.75 yd | 3.25 yd | 3.25 yd | 3.25 yd | 5.00 yd | 5.00 yd | 5.00 yd |
| 60 in | 2.75 yd | 3.25 yd | 4.00 yd | 4.00 yd | 5.00 yd | 5.50 yd | 5.75 yd |
| 70 in | 2.75 yd | 3.25 yd | 4.00 yd | 4.50 yd | 5.00 yd | 5.50 yd | 6.00 yd |
| 80 in | 4.00 yd | 5.00 yd | 5.00 yd | 5.00 yd | 7.50 yd | 7.50 yd | 7.50 yd |
| 90 in | 4.00 yd | 5.00 yd | 5.50 yd | 5.50 yd | 7.50 yd | 8.25 yd | 8.25 yd |
| 100 in | 4.00 yd | 5.00 yd | 5.75 yd | 6.00 yd | 7.50 yd | 8.25 yd | 9.00 yd |
| 110 in | 4.00 yd | 5.00 yd | 5.75 yd | 6.50 yd | 7.50 yd | 8.25 yd | 9.00 yd |
Chart: backing fabric to buy on wide backing, by quilt length and width
The same quilts on wide backing fabric with a hundred and four inches of usable width. Where the backing fits across the fabric it is cut as one piece.
| Quilt top width | |||||||
|---|---|---|---|---|---|---|---|
| Quilt top length | 40 in | 50 in | 60 in | 70 in | 80 in | 90 in | 100 in |
| 50 in | 1.50 yd | 1.75 yd | 1.75 yd | 1.75 yd | 1.75 yd | 1.75 yd | 3.00 yd |
| 60 in | 1.50 yd | 1.75 yd | 2.00 yd | 2.00 yd | 2.00 yd | 2.00 yd | 3.00 yd |
| 70 in | 1.50 yd | 1.75 yd | 2.00 yd | 2.25 yd | 2.25 yd | 2.25 yd | 3.00 yd |
| 80 in | 1.50 yd | 1.75 yd | 2.00 yd | 2.25 yd | 2.50 yd | 2.50 yd | 3.00 yd |
| 90 in | 1.50 yd | 1.75 yd | 2.00 yd | 2.25 yd | 2.50 yd | 2.75 yd | 3.00 yd |
| 100 in | 2.75 yd | 3.00 yd | 3.00 yd | 3.00 yd | 3.00 yd | 3.00 yd | 6.00 yd |
| 110 in | 2.75 yd | 3.25 yd | 3.50 yd | 3.50 yd | 3.50 yd | 3.50 yd | 6.00 yd |
Used by
- Quilt backing calculatorBacking fabric for a quilt of any size.