Room Planning guide

How to measure for curtains

Reviewed October 6, 2026 · By the Room Calculators team · How we check facts

Curtains are sized to the rod, not the window. Decide where the rod goes, measure from it, and then work out how many panels give the fullness you want.

1. Measure the window

For an outside-mounted rod, measure the window width from the outside edge of the trim on one side to the other.

2. Set the rod width

Extending the rod past the frame lets open curtains stack beside the glass instead of over it. Home Depot’s measuring guide suggests 8 to 10 in on each side for an outside mount; a 48 in window then takes a 64–68 in rod.

3. Choose the fullness

Fullness is the total flat width of the panels compared with the rod. About 2× gives a classic gathered look; 2.5–3× looks richer, and sheers are often hung fuller.

A 70 in window with 8 in each side takes an 86 in rod. At 2× that is 172 in of fabric; with 50 in panels, 3.44, so 4 panels (2 pairs).

4. Measure the length

Measure from where the curtain hangs (the rod, or the bottom of the rings) to the floor, then subtract the clearance you want: a small gap to hover, 0 to touch, or add length to puddle. Measure in more than one place; floors and rods are rarely perfectly level.

Rod height

Hanging the rod several inches above the frame, or partway toward the ceiling, makes a window look taller. Decide this before you measure length, since it changes the panel length you buy.

Reference: The Home Depot: How to Measure Curtains