Supported binding construction
This planner supports straight-grain, crosswise width-of-fabric strips for double-fold binding around a rectangular quilt with straight edges. Enter the strip width you intend to cut; the tool does not infer a finished binding width from batting thickness. Bias binding, curves, scallops, continuous-bias construction and mixed scrap-strip lengths need a different model.
Use the actual quilt edge size you plan to bind. If you are working from a projected finished seam-line size, the shared project control adds the two edge allowances to recover the raw top rectangle. Binding follows that outer edge rectangle, not the projected seam-line perimeter. After quilting and trimming, replace the estimate with actual measurements.
Two allowances with different jobs
The finishing reserve is total extra length beyond the perimeter for corners, handling and the final join of the binding ends. Intermediate strip-join loss is calculated separately. The default 12-inch reserve is a starting example, not a requirement for every technique. Change it to match your pattern or method.
For square-overlap diagonal joins, the ideal geometric length lost at each intermediate join is one cut strip width. For straight end joins, it is two joining seam allowances. The final end join is covered by the finishing reserve rather than counted as an additional intermediate seam. Extra overlap beyond a square join is not inferred.
The strip and yardage formulas
Perimeter = 2 × (raw edge width + raw edge length) Required working length = perimeter + finishing reserve Available length = N × usable WOF − (N − 1) × join loss Choose the smallest whole strip count N that covers the target Exact fabric depth = N × cut strip width Purchase depth = round the aggregate UP once
For diagonal joins, join loss equals cut strip width. For straight end joins, it equals twice the joining seam allowance. Usable fabric width must exceed the loss; adding strips of zero useful length cannot solve a plan.
Worked example: 60 × 80-inch quilt
The perimeter is 280 inches. A 12-inch finishing reserve makes the working target 292 inches. At 42 inches usable WOF and 2½-inch strips, seven strips provide 7 × 42 − 6 × 2.5 = 279 inches after diagonal joins, so they are insufficient. Eight provide 318.5 inches, including 26.5 inches beyond the target.
Eight strips consume 8 × 2.5 = 20 inches of bolt depth, or 0.5556 yards. Rounding up to ⅛-yard increments means buying ⅝ yard. The purchase rounding is performed after the whole strip count is known; displayed decimal results are not fed back into the count.
From borders to the binding bench
The border planner's result links carry the new raw width and length, seam convention and fabric settings here. The backing link keeps this same project. Changing a number does not silently rewrite the address or save your measurements. The explicit links contain numeric project settings, so someone with the link can read them.
Remeasure the trimmed quilt and check your sewing method before cutting. Shrinkage, fabric faults and quilting take-up are excluded. The schematic labels strip dimensions but is not a printable cutting pattern. The American Quilter's Society binding lesson explains a working reserve and diagonal joining. The per-join loss above is our geometric model, stated separately so it is not hidden inside an unspecified allowance.