Curtain Size Calculator
Work out curtain width and length for a window — rod width, fullness and drop — so curtains hang properly whether closed or open.
How to use
- 1Measure the window width and choose how far the rod extends past each side.
- 2Choose the fullness and the length style (sill, below sill or floor).
How it's calculated
Rod width = window width + 2 × extension. Total curtain width = rod width × fullness (1.5–2.5×). Length = rod height to sill/floor, minus ½ in clearance for floor length.
Frequently asked questions
How much wider than the window should curtains be?
For a full look, the combined curtain width should be 2 to 2.5 times the rod width; 1.5× is a lighter, flatter look.
Where should the rod go?
About 4–6 in above the window frame (higher makes ceilings look taller) and 3–10 in past each side so open curtains don't block light.
What length looks best?
Floor-length curtains that just skim the floor (about ½ in clearance) look most polished; sill length suits kitchens and radiators under windows.