Curtain calculator
Size curtains without guessing fullness.
Estimate rod width, fabric width, panel length, panel count, and fabric budget from window measurements.
Window and fabric inputs
Tip: 1.5x fullness looks tailored, 2x is common for bedrooms and living rooms, and 2.5x creates a heavier drape.
How this curtain estimate is calculated
The calculator starts with the visible window width, adds side return so the curtains can stack outside the glass, then multiplies by fullness. Fullness is the amount of fabric width compared with the rod width. A 2x fullness setting means the curtain fabric is roughly twice as wide as the rod.
Formula: rod width = window width + side return x 2. Fabric width target = rod width x fullness. Panel count = fabric width target / panel width, rounded up. Fabric yards = panel count x panel length / 36.
| Input | Why it matters | Practical note |
|---|---|---|
| Window width | Sets the base span the curtain must cover. | Measure the glass or frame depending on where the rod will sit. |
| Side return | Lets panels clear the window when open. | 6-10 inches per side is common for small to medium windows. |
| Fullness | Controls how flat or gathered the curtains look. | 1.5x is tailored, 2x is balanced, 2.5x is fuller and more formal. |
| Panel width | Determines how many panels are needed. | Use the finished panel width, not the fabric bolt width, for ready-made panels. |
Example: 72 inch window
A 72 inch window with an 8 inch return on each side needs an 88 inch rod. At 2x fullness, the target fabric width is 176 inches. If each panel is 54 inches wide, the project needs 4 panels after rounding up.
For a 60 inch tall window with 6 inches of extra drop, each panel is 66 inches long. Four panels need about 7.3 yards of fabric before considering hems, pattern repeat, shrinkage, or lining.
What changes the final purchase
- Pattern repeat that requires matching across panels.
- Blackout lining, interlining, or layered treatments.
- Floor-length curtains that need puddle or break allowances.
- Fabric shrinkage after washing or steaming.
- Rod hardware that sits far outside the frame.