Curtain Size Calculator
Size curtains like a decorator. Enter the rod or window width and the rod height above the floor in inches, choose a fullness multiplier (1.5× to 3×) and how the hem should meet the floor, and get per-panel width, curtain length, and the closest standard panel size.
Example: with Rod / window width (in) 60 · Rod height above floor (in) 84 · Fullness 2× — decorator standard · Hem style Float — 1/2 in above the floor · Panels 2 panels (split pair) → Width per panel: 60 in wide × 2 panels.
- Curtain length83.5 in (floats 1/2 in off the floor)
- Closest standard panel84 in standard panels (0.5 in longer — hem, or raise the rod)
- Total coverage width120 in of curtain width (2× fullness)
Computed by the calculator below using its default values. Change any input to see your own numbers.
Total curtain width = rod width × fullness (2× is the decorator standard). Length runs rod to floor: minus 1/2 in to float, plus 6 in to puddle.
Fullness is the number nobody tells you about
Curtains that merely span the window look like bedsheets on a rod. Ready-made panels are designed to be gathered, and the gathering ratio is called fullness: total curtain width divided by rod width. Decorators use 2× as the standard — a 60-inch window wants about 120 inches of curtain, or two 60-inch panels. 1.5× reads flat and tailored, 2.5× is generous, and airy sheers want 3× to drape well.
Length is measured from the rod (specifically where the ring or pocket tops out), not from the window. A half-inch float keeps hems clean and off the vacuum's path, brushing the floor looks intentional and blocks drafts, and a 6-inch puddle is a formal, high-maintenance look.
Buying versus sewing
Ready-made panels come in 63, 84, 95, 108, and 120-inch lengths and typically 50-54 inches of width. The calculator names the shortest standard length that reaches your target; if it overshoots by an inch or two you can hem it, raise the rod, or let a float become a brush. Widths rarely match exactly — round panel count up rather than accept skimpy fullness.
How it’s calculated
Total width = rod width × fullness (1.5, 2, 2.5, or 3). Width per panel = total ÷ panel count. Length = rod height − 0.5 in (float), + 0 (brush), or + 6 in (puddle). Standard US ready-made lengths compared against: 63, 84, 95, 108, 120 in.
Assumes the rod position sets the length — mounting the rod 4-6 in above the frame and extending 3-6 in past each side is the usual advice, and rings can add 1-2 in you should measure from.
Standard US curtain panel lengths
| Length | Typical use |
|---|---|
| 63 in | Sill-height and cafe windows |
| 84 in | Standard windows, 8 ft ceilings (most common) |
| 95 in | Rods hung high to fake taller windows |
| 108 in | Tall windows, 9 ft ceilings |
| 120 in | 10 ft ceilings and dramatic drops |
Standard ready-made lengths stocked by major US retailers; widths typically run 50-54 in per panel.
Common mistakes
- Buying panels only as wide as the window — without about 2× fullness, closed curtains look stretched and skimpy.
- Measuring the window instead of the rod: extensions past the frame add width you still have to cover.
- Ignoring ring drop — rings hang panels 1-2 in below the rod, which can turn a float into a drag.
- Grabbing one panel for a wide window because the package width technically covers it; gathered, it will not.
Frequently asked questions
What is the curtain width formula?
Total curtain width = rod width × fullness, then divide by the number of panels. A 60 in window at the standard 2× fullness needs 120 in of curtain — two 60 in panels.
How long should curtains be?
Measure from the rod to the floor, then subtract half an inch to float, use it exactly to brush, or add about 6 in to puddle. Floating is the practical default; sill-length suits kitchens and radiators.
How high should I hang the rod?
4-6 in above the window frame (or roughly two-thirds of the gap to the ceiling), extending 3-6 in past each side. Higher and wider makes windows read larger and lets more light in.
What fullness should I pick?
2× for most rooms. Drop to 1.5× for heavy fabrics or a tailored look, and go 2.5-3× for sheers, which need the extra gather to drape instead of hanging like a screen.