Curtain Size Calculator

in
in
in
Height of curtain rod from floor (only needed for floor-length).
Everyday Life

Calculate the ideal curtain width and drop (length) based on window dimensions and curtain style.

Formula

Width = window width × fullness multiplier; Length = window height + drop allowance
  • Standard fullness = 2× window width for a pleated, full look.
  • Sill length: add 4 in below sill. Below-sill: add 12 in. Floor: use rod-to-floor measurement.
  • Hemming: add 8–10 inches for top and bottom hems before purchasing fabric.

48-inch window, standard fullness, sill length

Inputs
  • Window Width: 48 in
  • Window Height: 60 in
  • Fullness Style: standard
  • Length Style: sill
  • Rod to Floor Distance: 84 in

Width = 48×2 = 96 in of fabric. Length = 60+4 = 64 in.

Frequently asked questions

How much wider than the window should curtains be?
At least 1.5× the window width; 2× is standard for a full look.
How long should curtains be?
Sill, apron (4 in below sill), floor, or puddle (3–6 in on floor for dramatic effect).
How many panels do I need?
Divide total needed width by panel width (typically 54 in), rounding up.
Should I add hem allowance?
Yes — add 8–10 inches for top rod pocket/header and bottom hem when buying fabric.