Quilt Backing Fabric
Calculator
Results
- Backing width (cm)
- 170
- Backing length (cm)
- 220
- Backing panels needed
- 2
- Fabric length needed (cm)
- 440
- Fabric length needed (m)
- 4.4
Craft results
| Backing width (cm) | 170 |
| Backing length (cm) | 220 |
| Backing panels needed | 2 |
| Fabric length needed (cm) | 440 |
| Fabric length needed (m) | 4.4 |
formula-map diagram
- Backing width (cm)
- 170
- Backing length (cm)
- 220
- Backing panels needed
- 2
- Fabric length needed (cm)
- 440
- Fabric length needed (m)
- 4.4
Formula breakdown
Formula
panels = ceil((W + 2o) ÷ fabric width) ; L = panels × (Lq + 2o)= 170
Note
Simplified model: these are standard craft estimates based on rectangular layouts, quoted gauge and nominal densities. Real fabric nap, directional prints, shrinkage, pattern matching, yarn lots and supplier SAP values vary, so always make a swatch or test piece and buy a little extra.
More in Crafts and sewing
See all →Frequently asked questions
Why does backing need to be bigger than the quilt top?+
Longarm quilters need extra fabric on all sides to load the quilt onto the frame and keep it taut, typically 4-8 inches of overhang per side. Without that margin the backing can shift or run out during quilting.
When do I need to piece the backing from multiple widths?+
Standard quilting fabric is about 40-42 inches wide, so any quilt wider than that needs the backing pieced from two or more panels sewn together, unless you use wide backing fabric (90-108 inches) sold specifically for this.
Does wide backing fabric change the yardage calculation?+
Yes, wide backing is priced and sold differently and often needs only a single length equal to the quilt's longest dimension plus overhang, with no piecing seam. Regular-width fabric needs the calculator's piecing logic to determine how many panels and how much total length to buy.
Should the seam in a pieced backing run horizontally or vertically?+
This is a layout choice, not something the yardage math forces, but a horizontal seam usually uses less fabric when the quilt is wider than it is tall, and vice versa. Either way, the calculator adds the extra length needed for the seam allowance where panels join.
Why does the result sometimes look wasteful for large quilts?+
Because backing must cover the full width in one direction, any excess beyond a clean panel multiple is unavoidable and gets rounded up. That leftover is normal and often ends up used for binding, borders, or a matching pillow.