Quilt BackingPlanner A little less waste.

FOUR WORKED STARTING POINTS

Quilt backing piecing examples

Use the planner’s Baby, Throw, Twin, and Queen quilt-top presets as starting points. Each example adds 4 inches on every side, then shows how two equal panels can make the finished backing.

Try a size in the planner

01 / READ THE ASSUMPTIONS

Targets are based on the selected overage

The planner presets are Baby 36 × 48, Throw 60 × 72, Twin 70 × 90, and Queen 90 × 100 inches. This page uses the planner’s default 4-inch overage on each side, so it adds 8 inches to both top dimensions. The presets are convenient examples, not universal quilt-size standards; check your actual top and your quilting setup.

Each sketch below uses two equal-width vertical panels and a ½-inch seam allowance on their inside edges. The seam allowance is consumed by sewing: both panels need an extra ½ inch at the joining edge, for 1 inch total across the seam. The outside edges have no joining seam allowance.

Finished panel width = backing target width ÷ 2

Cut width of each panel = finished panel width + ½ in at its joined edge

Cut length = backing target length

02 / COMPARE THE CUT SIZES

Two equal panels for each planner preset

In every row, sew the two long inside edges together with a ½-inch seam. The cut widths sum to the target width plus 1 inch; sewing removes that inch and leaves the target. Both panel lengths already equal the target length.

Two vertical panels · 4 in overage per side · ½ in seam allowance per joined edge
PresetQuilt topBacking targetCut each panel
Baby36 × 48 in44 × 56 in22½ × 56 in
Throw60 × 72 in68 × 80 in34½ × 80 in
Twin70 × 90 in78 × 98 in39½ × 98 in
Queen90 × 100 in98 × 108 in49½ × 108 in
Two panels joined to make a 68 by 80 inch Throw backingTwo panels each finish 34 by 80 inches. Cut each panel 34.5 by 80 inches so the half-inch seam allowance on each inner edge is sewn together, leaving 68 by 80 inches finished.Throw example · target 68 × 80 inPanel ACut 34½ × 80 inPanel BCut 34½ × 80 inEach inner edge includes ½ in seam allowance · finished width = 34 + 34 = 68 inDiagram not to scale · shaded center shows the allowances consumed by the seam
The example illustrates the same calculation used in the table. For another preset, substitute half of its target width and add ½ inch to each cut panel.

03 / ADAPT THE LAYOUT TO YOUR FABRIC

A simple two-panel seam is only one arrangement

The table assumes each piece of fabric is large enough to cut one full-length panel. If you have a measured 42 inches of usable width, the Baby, Throw, and Twin cut panels fit across it; the Queen panel needs 49½ inches, so it needs wider fabric or a different layout with more panels. A fabric labeled 42 inches may have less usable width after selvages are removed, so measure before deciding.

Directional prints may need to stay upright. You may prefer to add another panel, change the seam direction, or use wide backing fabric. The yardage guide compares bolt-length estimates for two seam directions and shows how to round to a store’s cut increment.

04 / WHAT THE PLANNER DOES

Use the tool to try your actual stash

The planner calculates the target from the quilt-top width and length plus the overage you choose. Its default seam allowance is ½ inch, and you can change it. It considers row and column layouts, allows a fabric piece to rotate only when you enable rotation, and uses at most one cut panel from each entered stash piece.

When the stash does not cover the target, the planner lists individual additional panels and their cut sizes. It does not reuse offcuts or turn those panels into a yardage estimate. Its suggested layout is not guaranteed to use the least fabric or fewest seams. Check the cut list, print direction, measured usable dimensions, and your quilter’s requirements before cutting.

For the underlying backing-size formula, visit the quilt backing size guide, then open the planner with your own dimensions.