Quilt Backing Calculator
Compare vertical and horizontal backing panels, then round the purchase length up to the increment you set.
Calculator
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Result
- Backing target
- 68 in (172.72 cm) × 88 in (223.52 cm)
- Recommended layout
- Vertical seams
- Purchase
- 5 yd (5 yd). Exact length 4.8889 yd, rounded up to the next 0.125 yd.
Overage is added to each side, so the backing is larger than the quilt by twice the overage in both directions.
Seam allowance is per raw edge. One seam joins two edges and consumes twice that allowance.
Joined coverage is n × usable width − 2 × seam allowance × (n − 1).
Purchase length is rounded up. Panel geometry is not rounded first.
When both orientations are allowed, the lower purchase length is recommended. An equal purchase keeps vertical seams.
Cut / purchase plan
Planning waste on the recommended layout is about 19% of the purchased area, including seam loss and unused width.
LayoutUse: vertical
Panels2
Seams1
Cut length88 in (223.52 cm)
Joined coverage83 in (210.82 cm)
Purchase5 yd (5 yd). Exact length 4.8889 yd, rounded up to the next 0.125 yd.
Layouthorizontal
Panels3
Seams2
Cut length68 in (172.72 cm)
Joined coverage124 in (314.96 cm)
Purchase5 3/4 yd (5.75 yd). Exact length 5.6667 yd, rounded up to the next 0.125 yd.
| Layout | Panels | Seams | Cut length | Joined coverage | Purchase |
|---|---|---|---|---|---|
| Use: vertical | 2 | 1 | 88 in (223.52 cm) | 83 in (210.82 cm) | 5 yd (5 yd). Exact length 4.8889 yd, rounded up to the next 0.125 yd. |
| horizontal | 3 | 2 | 68 in (172.72 cm) | 124 in (314.96 cm) | 5 3/4 yd (5.75 yd). Exact length 5.6667 yd, rounded up to the next 0.125 yd. |
How this calculation works
Backing width and height equal the quilt size plus overage on every side. A 4 in overage is the suggested start. A 5 in alternative is available in the form.
Joined coverage for n panels is n × usable width − 2 × seam allowance × (n − 1). The seam allowance is per raw edge, so one seam consumes two allowances.
Vertical seams size the panels from the backing width and cut them to the backing height. Horizontal seams do the reverse. The lower purchase is recommended only when the fabric may be turned.
Worked example
60 by 80 in quilt, 4 in overage, 42 in usable width, 1/2 in seam allowance
The backing target is 68 by 88 in.
Two vertical panels cover 83 in, which is enough for 68 in. Two panels at 88 in are 176 in, or 4.889 yd, which rounds up to 5 yd at 1/8 yd.
Horizontal seams need three panels and 204 in, which rounds up to 5.75 yd. The lower purchase is the vertical layout.
Assumptions and limitations
- Overage, usable width, seam allowance, and purchase increment are editable planning values.
- 42 in is a usable quilting width, not the nominal width printed on every bolt.
- Purchase rounding happens after the panel length is known. Geometry is not rounded first.
- Pieced leftovers, wide backing, and directional naps that are not aligned with the quilt edges are not optimized.
- The area-waste figure includes unused width and seam loss. It is not a prediction of the scrap shape.
Common questions
Why do both panel directions appear?
One direction often uses less fabric. Both are calculated so you can see the panel count, cut length, and purchase length before choosing.
What happens with directional fabric?
The calculator still shows both layouts, but it will not recommend the other direction. You choose the orientation the print must keep.