Window planning tool
Curtain size & fullness calculator
Turn measured hardware, side returns, overlap, and desired fullness into a conservative ready-made panel count before you order.
Plan panel coverage
Widths calculate in millimeters; finished length stays advisory.
1x is flat coverage with no added fullness.
Finished length is an advisory record and does not change the width result.
Diagram shows the relationship only; it is not an installation drawing.
Plan calculated
Curtain estimate: 4 ready-made panels; 188 in required flat width.
4 ready-made panels
188 in required flat width
Coverage before fullness: 94 in
Input recap
- Rod span
- 84 in
- Returns
- 3 in + 3 in
- Overlap
- 4 in
- Fullness
- 2x
- Panel width
- 50 in
- Finished length
- 96 in
Assumptions
- For operable, non-Ripplefold panel planning, coverage equals rod span plus both side returns plus center overlap.
- Panel width means the seller-stated flat width of one ready-made panel.
- Finished length is recorded for planning but does not change the width calculation.
Physical verification matters
Measure the installed rod and check the exact product specifications before ordering.
This estimate does not guarantee product fit; verify installed hardware, heading style, finished dimensions, and seller specifications.
Guidance and defaults
Source guidance: extend a rod about 6 to 12 inches past the window; use 1.5x to 2x fullness for many materials, while thin sheers may use 2.5x to 3x.
Formula provenance: for operable, non-Ripplefold panels, total coverage includes the rod span, both returns, and center overlap. The hardware retailer guide states the inverse formula for existing panels; this calculator rearranges it for required coverage. Center overlap applies to split-draw traverse rods.
Editorial defaults: 84-inch rod span, 3-inch returns, 4-inch overlap, 50-inch panel width, and 96-inch finished length. The starting measurements are editable examples, not sourced recommendations. The 2x fullness default is within the sourced guidance range.
Source check: July 10, 2026.
How the estimate works
Coverage = rod span + left return + right return + center overlap. Required flat width = coverage x fullness. Panel count divides that width by the seller-stated flat width per panel and rounds upward.
Worked width comparison
Curtain fullness and panel count chart
This example uses 100 inches (254 centimeters) of total coverage and a seller-stated 50-inch (127-centimeter) flat width per ready-made panel.
| Fullness | Required flat width | Metric equivalent | 50-inch panel example |
|---|---|---|---|
| 1x flat | 100 in | 254 cm | 2 panels |
| 1.5x | 150 in | 381 cm | 3 panels |
| 2x | 200 in | 508 cm | 4 panels |
| 2.5x | 250 in | 635 cm | 5 panels |
| 3x | 300 in | 762 cm | 6 panels |
This is a worked comparison only; it does not choose a fullness level or panel. Measure the installed hardware and use the seller-stated flat width of the exact panel.
Guidance checked 2026-07-10. See Guidance and defaults for sources and formula limits.
Guides for this calculation
Check the measurements, assumptions, and worked examples in the related guides. Return to Windows planning for the full decision sequence, or review the tool methodology for formulas and limits.