Curtains hung too short or too skimpy can cheapen an otherwise luxurious room instantly. Designers have firm rules — rods mounted high and wide, panels with generous fullness — but translating those rules to your window means doing math most of us would rather skip. Our curtain size calculator does it for you.

The two numbers that matter are width and length. Width determines fullness (those rich, gathered folds need 2 to 2.5 times your window width), and length determines whether your curtains kiss the floor or puddle elegantly. Get either wrong and the whole window looks off.

How the curtain size calculator works

Enter your window’s width and height, choose your desired look — sill, below-sill, or floor-length — and the calculator returns the exact panel width and length to buy. It factors in fullness ratios automatically, so you won’t end up with flat, stretched panels that barely close.

Hang them like a designer

The pro move is mounting your rod 4 to 6 inches above the window frame and extending it 3 to 6 inches beyond each side — it makes windows look larger and ceilings taller. Pair that placement with correctly sized panels and even ready-made curtains look custom. For more ways to elevate your space, explore our elegant home decor ideas that feel truly premium.

Measure once, hang beautifully.