Quilt Binding Calculator

Binding runs around the perimeter of the quilt — 2 × (width + length) — plus extra for the mitered corners and the diagonal join where the two ends meet. This calculator uses 10 inches as an adjustable planning default; use the allowance in the binding method or pattern you will follow. Then divide by the usable length of one strip: a strip cut across 42-inch-wide quilting cotton yields about 40 inches once the selvage is trimmed away.

The default 2½-inch strip width suits a standard ¼-inch seam and produces a finished binding of about ⅜–½ inch on the front. Mini quilts often use 2-inch strips; a chunky ¾-inch finished binding wants 3-inch strips. Whatever you enter, the fabric total is simply strips × strip width, converted to yards and rounded up to the nearest ⅛ — the purchasing increment this calculator models. Check the increment your seller offers.

Strip width sets the finished binding. A common double-fold choice is 2½ inches; with a ¼-inch seam it usually finishes around ⅜–½ inch on each face, depending on batting loft and exactly where the seam lands. Miniatures may use narrower strips, while high-loft projects may need more width. Treat the pattern and a short test section as the authority rather than assuming one width fits every edge.

Width also changes the fabric bill because every strip costs its cut width off the bolt. Enter the planned cut width in the calculator instead of scaling a table by eye. Whatever width you choose, keep it consistent: strips of different widths sewn into one binding produce an uneven finished edge.

Cross-grain strips cut across the width of fabric are the economical, stable choice for most straight-edged quilts. Bias strips are needed for curved or scalloped edges, where a straight strip will not lie flat; their diagonal grain supplies the necessary give. Bias also distributes threads across the fold differently, but fabric type and use matter more than a blanket durability promise.

Bias yardage is a layout problem, not a fixed multiplier. For continuous bias, a square of side S has a theoretical yield of S² ÷ strip width before trimming and seam loss: an 18-inch square at 2½ inches yields about 130 inches. Use that formula to size the square, then add the allowance required by the continuous-bias method you follow. This calculator and the table below model cross-grain strips, so do not reuse their fabric column as a bias-cut shopping figure.

Join strips end-to-end with a diagonal seam, pressed open. The seam line runs about 3½ inches across a 2½-inch strip (width × √2), spreading the seam bulk along a diagonal instead of concentrating it in one crosswise ridge.

Every diagonal join consumes some length because the strips overlap before sewing. Enter a net usable strip length after selvage trimming and join handling; the default 40 inches is a conservative planning value for common quilting-cotton widths. The separate 10-inch allowance is for turning corners and completing the final join, not a claim that internal joins are lossless. Round up and keep a little extra rather than sizing binding to the perimeter alone.

The table below is computed with this calculator’s exact formula — perimeter plus a 10-inch allowance, divided into a conservative 40-inch net strip length, with fabric rounded up to the nearest eighth yard — for six common finished sizes using 2½-inch strips. Read it as a planning check, then replace the defaults with the measured usable width and the binding instructions for the actual project.

Square and trim the quilt sandwich before measuring its perimeter. Wavy borders or an edge pulled out of shape need correcting before the binding goes on; the yardage formula cannot flatten them. Sew with even feed if the layers shift, and guide the strip without stretching it around straight edges.

At each square corner, stop one seam allowance from the edge — a quarter inch only when using a quarter-inch seam — before folding the mitre. Keep the seam allowance consistent on both faces and check the corner before trimming; small differences in batting loft and strip width change where the fold naturally sits.

Take a throw quilt that finishes at 60 × 72 inches, bound with 2½-inch strips cut from 40-inch usable width. The perimeter is 2 × (60 + 72) = 264 inches. Add 10 inches for corners and the join: 274 inches of binding. Divide by 40 and you get 6.85 — so cut 7 strips. Seven strips at 2½ inches is 17½ inches of fabric length, or 0.486 yards — buy half a yard and you will have the scraps for the diagonal joins and a practice corner.

Cutting tip: join the strips with diagonal seams pressed open rather than square joins so the seam bulk is distributed. Cut cross-grain strips for a typical straight-edged quilt; use a separate bias-binding layout for scalloped or curved edges.