Quilt Backing & Binding Calculator
Most free calculators stop at the backing. This one does the backing three ways — vertical piecing, horizontal piecing, and wide-back — and the binding: strips to cut, binding yardage, and a cut diagram that redraws itself as you type.
Backing — vertical piecing
- Pieces to cut
- Cut each piece
- Seams
- Exact yardage
Seams run along the length of the quilt.
Backing — horizontal piecing
- Pieces to cut
- Cut each piece
- Seams
- Exact yardage
Seams run across the width of the quilt.
Backing — wide-back fabric
- Pieces to cut
- Cut each piece
- Seams
- Exact yardage
One piece, no seams, whenever one width covers either backing dimension.
Binding
- Perimeter
- Binding needed (+10")
- Strips to cut
- Fabric for strips
The +10" covers mitered corners, the final join, and tails.
Cut diagram
Backing layout for:
The dashed rectangle is your quilt top; the border around it is the extra margin, which gets trimmed after quilting. Diagram is to scale for shape, not for print.
How the math works
Backing size
Your backing must be bigger than the quilt top on every side, so the quilter can load, baste, and square up. The calculator adds your margin twice per dimension: backing width = top width + 2 × margin, and the same for length. With the common 4" margin, a 60" × 80" top needs a 68" × 88" backing.
Piecing the backing
Standard quilting cotton is only about 42" wide, so most backings are sewn from several widths of fabric. Two layouts are possible:
- Vertical piecing — widths stand side by side, seams running along the quilt's length. Pieces needed = enough widths to cover the backing width after each seam eats 2 × your seam allowance; each piece is cut to the full backing length.
- Horizontal piecing — widths stack top to bottom, seams running across. Pieces needed = enough widths to cover the backing length; each piece is cut to the full backing width.
Neither is "correct" — the calculator totals both so you can buy whichever uses less fabric. Often the layouts differ by three quarters of a yard. Total yardage for either = pieces × cut length ÷ 36, rounded up to the nearest ⅛ yard, because that is how fabric is cut and sold.
Wide-back fabric
Wide backing (usually 108") skips piecing entirely whenever one width covers either backing dimension — the calculator rotates the piece to whichever orientation cuts less. If your quilt is bigger than the wide fabric both ways (king quilts, usually), it reports the two-piece wide-back layout instead of pretending one piece works.
Binding
Binding wraps the quilt top's edges, so it is figured from the top, not the oversized backing: binding length = 2 × (width + length) + 10". Strips needed = that length ÷ your fabric width, rounded up, because a strip cannot give you more binding than its width. Binding yardage = strips × strip width. Full walkthrough on the binding yardage guide.
Worked check — 60" × 80" quilt, 4" margin, 42" fabric: backing 68" × 88". Vertical: 2 widths cover the 68" (84" before seam loss), each cut 88" → 176" total → 5 yards to buy. Horizontal: 3 widths cover the 88", each cut 68" → 204" → 5¾ yards. Wide-back: one piece cut 68" → 2 yards. Binding: perimeter 280" + 10" = 290" → 7 strips of 2.5" → ½ yard. Type those numbers in above and watch it agree.
Keep going
The full method, with the seam-allowance trap most quick calculators skip.
Where the +10" comes from, strip counts, and 2.25" vs 2.5" strips.
Cost, seams, and when the wide fabric is genuinely the cheaper choice.
Crib through king, with backing and binding already figured for 42" fabric.