Ceiling Fan Size Calculator
Find the right ceiling fan blade span for any room.
Returns recommended diameter from 42 to 60 inches based on room square footage and ceiling height.
How to Choose Ceiling Fan Size for a Room
A ceiling fan that’s too small won’t effectively circulate air; one that’s too large creates uncomfortable drafts and wastes energy. Proper sizing is based on room square footage (or square meters).
Room Area Formula:
Area = Length × Width
Fan Blade Span Selection Guide. These are the bands the American Lighting Association publishes, and the ones this calculator uses.
| Room Size (ft²) | Room Size (m²) | Blade Span |
|---|---|---|
| Up to 75 ft² | Up to 7 m² | 29–36" (74–91 cm) |
| 76–144 ft² | 7–13 m² | 36–42" (91–107 cm) |
| 145–225 ft² | 13–21 m² | 44–50" (112–127 cm) |
| 226–400 ft² | 21–37 m² | 50–54" (127–137 cm) |
| Over 400 ft² | Over 37 m² | 54–72" (137–183 cm), or two fans |
Worked Example: Master bedroom: 4.5 m × 4 m = 18 m², which is 194 ft². That falls in the 145 to 225 band, so a 44–50 inch (112–127 cm) fan.
Two fans beat one oversized fan in a long room. A 6 m by 3.5 m living space is 226 ft² and technically calls for a 54 inch fan, but a single fan in the middle leaves both ends still. Two 44 inch fans spaced along the length move air everywhere and run quieter, because neither has to work at full speed.
Airflow (CFM) Rating: Higher CFM = more air moved per minute. For effective cooling:
- Small rooms (7–14 m²): 2,000–4,000 CFM
- Medium rooms (14–25 m²): 4,000–6,000 CFM
- Large rooms (25–40 m²): 6,000–9,000 CFM
Installation Height: Fan blades should hang 2.1–2.4 m (7–8 feet) above the floor for optimal circulation. For 2.7m+ ceilings, use a downrod extension to drop the fan to the proper height. For low ceilings under 2.4m, use a flush-mount (hugger) design.
Seasonal Direction:
- Summer: counterclockwise (viewed from below), which pushes air straight down
- Winter: clockwise at low speed, which pulls cool air up and pushes warm air down from the ceiling
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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