Quilt backing & sashing calculator
Give it the finished width and height of the top, the backing width you're buying and the overage you want on each side, and it returns the yards of backing. Tick sashing and add the block grid if you want sashing yards as well. The panel and strip maths match the yardage and binding calculators, and the whole thing runs in your browser.
A 60 by 72 inch throw with 4 inches of overage on 40 inch backing, sashing off: the sample default is 4.0 yards of backing.
- 42 in or 108 in backing, optional sashing
Finished size → yards
Retail widths: 42 in quilting cotton (about 40 usable) or 108 in wide backing.
Added on every side for quilting and trimming.
Used for sashing cut width only.
Continuous strips, no cornerstones.
- Backing yards
- —
- Cheaper piecing direction
- Sashing yards
- —
- From ~40\" WOF
Each part is rounded up to the nearest quarter yard, as on the yardage calculator.
Size reference (4" overage each side)
42 in quilting cotton (about 40 usable) vs 108 in wide backing
| Finished top | 40" backing | 108" wide back |
|---|---|---|
| 36 × 52 (baby) | Run the numbers above | Usually one panel |
| 60 × 72 (throw) | 4.0 yd (sample default) | Enter 108 as width to compare |
| 90 × 100 (queen-ish) | More panels / yards | Often far fewer yards, no seam |
For the throw, the backing piece is 68 by 80 inches. Two 40 inch panels cut 68 inches long come to 136 inches, which rounds up to 4.0 yards. Running the seam the other way takes 160 inches, or 4.5 yards.
Free backing calculators exist, such as Quilt Math. This page adds optional sashing and uses the same panel math as the yardage calculator, so the two never disagree.
How the math works
- Backing piece = finished size + overage on every side.
- Panels from your backing width in both directions; buy the cheaper.
- Optional sashing: cut width = finished + 2 × seam; strip count from total strip length ÷ 40.
Questions
Do free backing-only calculators already exist?
Yes. Free backing calculators exist, such as Quilt Math. This page adds optional sashing and uses the same panel math as the yardage calculator, so the two never disagree.
Is this the same as the yardage calculator?
It is a sibling focused on backing (and optional sashing). Full blocks, borders, binding and backing together still live on the yardage calculator. Binding-only strip math stays on the binding calculator. The formulas here match those tools, so a quilt worked out on any of them comes to the same yardage.
42 inch or 108 inch backing?
Type the usable width of what you will buy. Quilting cotton is sold 42 inches wide, which leaves about 40 usable once the selvages are trimmed. Wide backing is sold 108 inches wide. The calculator works out both piecing directions and keeps whichever needs fewer yards.
Does sashing use wide-back width?
No. Sashing strips are assumed cut from standard ~40 inch usable quilting fabric. Backing width only affects the backing panels.
What about cornerstones?
This tool assumes continuous sashing strips without cornerstones, the same model as the sashing option on the binding calculator.
I quilt for clients. What next?
Custom floor prices: the commission quote kit. Cents per square inch for tops on your frame: the longarm rate planner. Both together are the Quilter who sells pack ($49 planned).
Updated