Measure windows for fabric, panels, rods, and finished drop
Window treatments depend on where the rod or track sits, the finished width, the desired fullness, and the finished drop. Glass size alone is rarely enough. Curtains also need header, hem, pattern, and panel decisions before fabric can be converted into a purchase quantity.
Measure each window rather than assuming repeated openings are identical. Record the final hardware position first, because changing the rod width or height changes the curtain dimensions that follow.
Before you calculate or buy
- Decide whether the treatment sits inside the reveal, on the frame, or beyond it.
- Measure finished track or rod width and finished drop at more than one point.
- Choose fullness before calculating panel or fabric width.
- Check fabric width, pattern repeat, heading, hems, and matching requirements.
- Confirm that rods, brackets, and fixings suit the span and wall construction.
Common mistakes to avoid
- Using window-glass width as the curtain width without rod extension or fullness.
- Measuring from the ceiling or floor before the hardware position is decided.
- Ignoring a large pattern repeat when estimating fabric length.
- Assuming all windows in the same room have identical dimensions.
Detailed walkthrough: Curtains: from window measurement to fabric order
Reviewed 19 September 2026. Confirm the mounting position, track or pole dimensions, fullness, returns and the maker’s measurement rules.