How Much Electricity Does a Box Fan Use?

A standard 20-inch box fan uses between 45 and 85 watts depending on the speed setting, costing between 0.8¢ and 1.6¢ per hour at the national average rate of 18.34¢ per kWh. Running a box fan continuously for 24 hours a day costs roughly $7.50 to $11.40 per month. Compared to a 1,000-watt window air conditioner costing 18.3¢ per hour, a box fan consumes roughly 93% less electricity.

Key takeaways

• Low speed draws roughly 45 to 55 watts (0.8¢ to 1.0¢ per hour).
• Medium speed draws roughly 60 to 70 watts (1.1¢ to 1.3¢ per hour).
• High speed draws roughly 75 to 85 watts (1.4¢ to 1.6¢ per hour).
• Fans cool people via evaporative convective cooling, not by reducing room air temperature.

Wattage breakdown across fan speeds

Most consumer box fans use fractional-horsepower shaded-pole or permanent split capacitor (PSC) AC induction motors. Shaded-pole motors are inexpensive but have modest electrical efficiency. On setting 1 (Low), the motor draws around 48 watts. On setting 2 (Medium), draw rises to 62 watts. On setting 3 (High), the motor operates near 80 watts.

If you use a box fan in your bedroom for 8 hours each night on medium speed, it consumes roughly 0.5 kWh per night. That equals 15 kWh per month, costing just $2.75 on your electric bill. You can calculate custom hours and rates using our box fan electricity calculator or compare it against overhead airflow with the ceiling fan monthly cost guide.

Using box fans for window cross-ventilation

A box fan placed in a window facing outward can act as an exhaust fan during cool evening hours, pulling warm air out of the house while open windows on the shaded side draw in cool outdoor air. Moving 1,800 to 2,200 CFM of air through the house cools interior thermal mass using 75 watts, avoiding the need to run an energy-heavy air conditioner during evening hours.

When outside temperatures drop below 70°F, turning off the air conditioner and running two box fans creates whole-house airflow on 150 watts total, saving 1,000 to 2,500 watts of central air compressor load.

Fans cool people, not empty rooms

Electric fans do not lower room air temperature. The motor actually adds a small amount of heat to the room. The cooling effect comes from the wind chill of moving air speeding up the evaporation of moisture from human skin. Leaving a box fan running in an unoccupied room wastes electricity without cooling the space.

FAQ

How much does it cost to run a box fan 24/7 for a year? Running a 60-watt box fan continuously 24 hours a day for 365 days consumes 525.6 kWh, costing about $96.40 per year at 18.34¢ per kWh.

Is a box fan cheaper to run than a tower fan? Tower fans with DC brushless motors often draw 15 to 35 watts, making them 40% to 60% cheaper to run than a traditional AC box fan, although box fans typically move more total cubic feet of air per minute.

Can a box fan run on a portable solar power station? Yes. Because a box fan draws only 50 to 80 watts, a standard 500-watt-hour portable power station can run a box fan for 6 to 9 hours on a single charge.

Data notes & sources

Measurements reflect bench testing of standard 20-inch three-speed residential box fans under normal room temperature conditions.

Home cooling efficiency: Department of Energy Fans for Cooling.

EIA state electricity prices: U.S. EIA Electric Power Monthly Table 5.6.A.