QUILT PLANNING / BACKING
42-inch vs 108-inch quilt backing
Wide-back fabric can eliminate piecing, but “108 inches” on the label does not guarantee 108 usable inches. Compare measured widths before comparing yardage.
Nominal width and usable width
This guide compares 42 in usable regular fabric with a 108 in wide-back bolt modeled as 106 in usable after trimming. The two-inch reduction is an example, not a rule for every fabric. If your cloth measures 108 usable inches, enter 108 in the calculator.
↔ Swipe or scroll sideways to compare all columns.
| Example quilt top | 42 in usable | 106 in usable wide-back |
|---|---|---|
| Crib · 36 × 52 in | 2 1/2 yd · 2 panels | 1 1/4 yd · 1 panel |
| Throw · 50 × 60 in | 3 1/4 yd · 2 panels | 1 5/8 yd · 1 panel |
| Twin · 70 × 90 in | 5 1/2 yd · 2 panels | 2 1/4 yd · 1 panel |
| Queen · 90 × 100 in | 8 1/4 yd · 3 panels | 3 yd · 1 panel |
| King · 108 × 108 in | 9 3/4 yd · 3 panels | 6 1/2 yd · 2 panels |
Assumes 4 in extra on every side, ½ in seam allowance on each joined edge, and the lower-yardage full-panel layout. The wide-back column models a 108 in fabric with 106 in usable after trimming; measure your own cloth. A 90 × 100 in top needs a 98 × 108 in back: the 106 in width covers the 98 in side, so one 108 in length works. Purchases round up to the next ⅛ yd. Sizes are examples, not bed-size standards. Shrinkage, print matching and additional squaring waste are excluded.
A queen-size example with no backing seam
A 90 × 100 in top with 4 in extra per side requires a 98 × 108 in backing. The 106 in usable width covers the 98 in dimension; cut 108 in down the bolt and buy 3 yd. With 42 in usable fabric, the lower-yardage full-panel layout requires three 98 in cuts, rounded to 8¼ yd.
A wide back is not always seamless
A 108 × 108 in king top needs 116 × 116 in with those allowances. Neither 106 nor 108 usable inches covers it in one panel. Our full-panel calculation uses two 116 in cuts, rounded to 6½ yd at 106 usable inches. A carefully planned narrow add-on strip may use less, but requires a different layout than this calculator models.
Compare price and print direction
Multiply each yardage by its price per yard. In the queen example, compare 3 × the wide-back price with 8.25 × the regular price. Add seam work, print matching and shrinkage to your decision. A one-way motif may prevent rotating the backing.
Read our calculation methods and limits. Examples use the same arithmetic as the calculators and are planning estimates, not independently field-tested sewing instructions. Confirm allowances with your quilter.