Curtain Size Calculator: What Size Curtains Do I Need?

Hang Curtains High and Wide

The single biggest upgrade you can make to a window is to hang the curtains high and wide. Builder-standard rods sit just above the frame and barely wider than the glass, which makes windows look small and ceilings look low. The calculator instead positions the rod to make the window look larger than it is.

• Wide: the rod extends 8 to 12 inches (20 to 30 cm) past the window frame on each side. When the curtains are open, the panels stack against the wall instead of covering glass, so you get more daylight and a wider-looking window.
• High: the rod mounts 4 to 6 inches (10 to 15 cm) below the ceiling or crown molding. If your ceilings are very tall, mount it at least 4 to 6 inches above the frame and consider going higher for drama.

So for a 48-inch-wide window, the rod spans roughly 64 to 72 inches, not counting finials.

Calculating Curtain Width and Panel Count

Curtains look best when they have enough fabric to fall in soft folds even when closed. That extra fabric is called fullness. The calculator multiplies your rod width by your chosen fullness to get the total curtain width, then divides by the panel width and rounds up.

Example: a 48-inch window with the rod extending 10 inches on each side gives a 68-inch rod. At standard 2× fullness, you need 136 inches of fabric. With 54-inch panels, 136 ÷ 54 = 2.5, so round up to three panels; with 50-inch panels, 136 ÷ 50 = 2.7, also three. Many people buy four panels (two pairs) for a fuller look and symmetry.

Choosing Curtain Length

Measure from the rod (or from the bottom of the rings or clips, if you use them) to the floor. Then pick a length style:

Ready-made panels come in standard lengths of 63, 84, 95 or 96, 108, and 120 inches. The calculator picks the closest standard length that achieves your style. If no size is exact, choose the next length up and hem it, or nudge the rod an inch or two higher or lower. Avoid 63-inch panels in living spaces unless they are café curtains; they almost always look short.

Common Window Scenarios

In a typical apartment with 8-foot (96-inch) ceilings, mounting the rod 4 inches below the ceiling leaves about 92 inches to the floor, so 95- or 96-inch panels will give a slight break, or can be hemmed to float. With 9-foot ceilings, 108-inch panels usually work. For a wall of windows, run one continuous rod across the whole wall and let panels stack at each end.

If a radiator, window seat, or built-in sits below the window, sill-length or apron-length curtains are acceptable, but full-length curtains on a rod that extends well past the obstacle still look more finished.

Curtains in a Rental

Most leases allow small screw holes for curtain hardware, but check first. Tension rods work inside window recesses but cannot hang high and wide. Look for no-drill brackets that clip onto window frames, or ask your landlord whether you can replace the existing low rod. When you move, fill screw holes with spackle and touch up the paint.

High, wide, floor-length curtains are one of the most effective tricks in our guide to how to make your apartment look expensive. For more ways to frame windows and seating, explore our apartment living room ideas, apartment bedroom ideas, and renter friendly upgrades.