Calculated result
Adjust the editable example, then select Calculate.
Method and assumptions
Backing width and length each add twice your per-side extra. For each orientation, the joined usable width of n strips is n × fabric width − 2 × seam allowance × (n − 1). The tool finds the smallest n covering the required crosswise dimension, then multiplies n by the length of each cut. Waste percentage is applied to total cut length. Both orientations are shown; no hidden purchasing increment is added.
Worked example
A 58 × 66-inch top plus 4 inches per side needs 66 × 74 inches of backing. With 42-inch usable fabric and 0.5-inch joining allowance, two 74-inch lengths use 148 inches, or 4.111 yards, for lengthwise seams; two 66-inch lengths use 132 inches, or 3.667 yards, crosswise.
Limits of the estimate
The two orientations assume straight full-width pieces and no pattern matching. Directional print, selvage removal, prewashing, seam placement, grain, and longarm requirements may change your real cut. Ask your quilter for their required extra.
Privacy
Measurements and results stay in this browser tab. The calculator does not send input values, store them, or place them in the URL. No account or upload is required.