A typical 20-inch box fan uses about 75 watts, roughly 40 W on low to about 110 W on high depending on the model. There is no meaningful startup surge.
- Running watts
- 75 WTypical; 40–110 W across models
- Starting watts
- NoneNo motor surge
- Per day
- 0.6 kWh8 h of use
- Current
- 0.6 AAt 120 V while running
Figures checked against DOE, ENERGY STAR and manufacturer data on . Your model's label is the final word.
Watts by model and setting
Most box fan models draw between 40 and 110 W while running; a typical one draws about 75 W. Assumes about 75 W for 8 hours of use.
- Speed setting: low speed draws noticeably less than high
- Motor efficiency: some 20-inch fans are rated around 55 W on high
- Fan size and blade design
- Age and dust on the blades and motor
Running a box fan on a generator or power station
- Generator: at least 75 running watts. A generator rated 1,000 W or more covers it with room to spare.
- Power station: continuous output of at least 75 W. Pure sine wave output is the safe choice for motors and electronics.
| Power station capacity | Estimated runtime |
|---|---|
| 500 Wh | 5.7 h |
| 1,000 Wh | 11.3 h |
| 2,000 Wh | 22.7 h |
| 3,000 Wh | 34 h |
Based on 75 W average draw and 85% usable capacity.
- Box fans are a good outage cooling option: a 500 Wh power station runs one for about 5-6 hours on high
- Any small generator can run several box fans
- Most box fans run fine on modified sine wave power, but they may hum; pure sine wave is quieter
- Keep the generator outdoors and do not point a window fan in a way that could draw generator exhaust inside
Add it to the generator calculator
Questions people ask
How much does it cost to run a box fan all night?
About 0.6 kWh for 8 hours at 75 W, or around 9 cents at 15 cents per kWh. Lasko says its 3733 model costs less than 2 cents an hour.
How long will a power station run a box fan?
Divide usable watt-hours by the fan's watts: a 1,000 Wh station runs a 75 W fan for roughly 11-12 hours after inverter losses.