Curtain Size Calculator — Free Online Tool
Skimpy curtains that barely cover the window ruin the look of a room. This curtain size calculator multiplies your window width by the fullness factor designers use, and sets the length properly.
What is the Curtain Size Calculator?
Curtain width should be 1.5–2× the window width — 2× gives rich, full gathers; 1.5× is tailored and modern. That total width is split across two panels for most windows. Length: mount the rod 4–6 inches above the window frame and let panels kiss the floor or puddle slightly — short “sill-length” curtains date a room instantly.
Extend the rod 3–6 inches past the frame on each side so open curtains don't block light. This curtain size calculator adds 10 inches to window height for the above-frame mount and floor break, and multiplies width by your chosen fullness. For wide windows or sliders, consider three panels instead of two.
How to use this calculator
- Measure the window width and height in inches.
- Choose fullness: 2.0 for full gathers, 1.5 for tailored.
- Click Calculate Curtains for total width and length.
- Mount the rod 4–6" above the frame and 3–6" wider each side.
Formula
Frequently asked questions
Should curtain fullness be 1.5 or 2?
2× gives luxurious full gathers; 1.5× looks tailored and modern. This curtain size calculator supports both.
How high should I mount curtain rods?
4–6 inches above the window frame — higher makes ceilings feel taller.
Should curtains puddle or just touch the floor?
Just kissing the floor is the safe modern choice; a slight puddle suits formal rooms. Avoid floating above the floor.
How wide should the curtain rod be?
3–6 inches past the frame on each side, so open panels clear the glass fully.