Case 1
- Room length
- 2.5m
- Room width
- 2.5m
82.55cm
Open with these valuesCeiling Fan Size Calculator
119.38cm
Result: 119.38 cmThe recommendation is really a range — 44 to 50 inches for a mid-sized room, for instance. This shows the middle of that range; anything inside it is fine. Only the floor area matters, so a long narrow room takes the same fan as a square one of equal size.
Worked examples
Case 2
- Room length
- 5m
- Room width
- 4m
119.38cm
Open with these valuesCase 3
- Room length
- 8m
- Room width
- 6m
160.02cm
Open with these valuesHow it's calculated
area → band → middle of the blade span
- StepSwitch the units above if you work in feet and inches.
- StepEnter the length and width of the room.
- ResultRead the suggested blade span and check it against the range below.
What this number means
The number is the middle of a range
Every area falls into a band, and the calculator returns the middle of that band. A 5 by 4 metre room lands in the 112 to 127 cm band and comes back as 119 cm. Any span inside the band is a sound choice.
Only the floor area decides
Length times width is all the formula uses, so 5 by 4 and 4 by 5 both return 119 cm. A long narrow room takes the same fan as a square one of equal area.
Ceiling height is a separate question
The span follows from the area alone, which is why there is no height field here. How far the fan hangs below the ceiling is set by the downrod, and that is chosen separately.
The band limits are whole square feet
The bands run to 75, 144, 225 and 400 ft², which in metres are the untidy 6.96, 13.37, 20.90 and 37.16 m². A room sitting right on one of those figures can fall either side, so hold a borderline result against the table above.
Commonly misread
I measured one blade and took that as the span.
Blade span is measured tip to tip across the whole circle the blades sweep. That is the figure printed on the fan, and the one this calculator returns.
My room is long and narrow, so a smaller fan will do.
Only the area counts here. A 4 by 5 metre room and a 5 by 4 metre room both come back at 119 cm.
It says 119 cm, so only a fan of exactly 119 cm fits.
119 cm is the middle of the 112 to 127 cm band for that area. Anything inside the band works.
My ceiling is low, so I picked a smaller fan.
Height changes the downrod, not the span. The area sets the diameter, and that is exactly why there is no height field.
Reference table
| Room area | Blade span |
|---|---|
| Up to 75 ft² / 6.96 m² | 29–36 in / 74–91 cm |
| Up to 144 ft² / 13.37 m² | 36–42 in / 91–107 cm |
| Up to 225 ft² / 20.90 m² | 44–50 in / 112–127 cm |
| Up to 400 ft² / 37.16 m² | 50–54 in / 127–137 cm |
| Larger | 54–72 in / 137–183 cm |
Questions
What size fan does my room need?
Only the floor area decides. A 5 by 4 metre room gives 119 cm, a 3 by 3 room gives 99 cm and a 8 by 6 room gives 160 cm — the same fan for a long narrow room as for a square one of equal area.
Is the answer a single size?
No, it is the middle of a range. The table above shows the band each area falls into, and any span inside that band is fine.
How is blade span measured?
Tip to tip across the whole circle the blades sweep, not the length of one blade. That is the figure manufacturers print, and the one this calculator returns.
Does ceiling height change the size?
Not the span. Height decides the downrod and how far the fan hangs, and the calculator has no field for it because the area alone sets the diameter.
Sources and last check
Information, not professional advice.