How the figure is calculated
A fan motor draws close to its rated power the whole time it spins, so watts × hours is a fair estimate. We divide the watts by 1,000 to get kilowatts, multiply by the hours you enter, then by your price per kWh. US box, pedestal and circulator fans use the manufacturer’s stated input power per speed; Hunter ceiling fans use watts measured in the DOE Appendix U lab test, which is more precise than a nameplate.
There is no official figure for how long people run a portable fan, so we do not invent one. The cost per hour is the headline; type your hours for daily and monthly totals.
What drives the cost
Motor type beats size. A DC-motor circulator like the Meaco 1056P peaks at 24 W, while a traditional 20-inch box fan pulls 83 W on high. Speed setting is the other lever: the Lasko B20308 drops to 56 W on low, and the Hunter 52-inch Brazos ceiling fan goes from 18.0 W on high to 2.1 W on low.
Worked example
US: the Lasko Cool Colors B20308 on high is 83 W. At 18.31¢/kWh that is 1.52¢ an hour; run it 8 hours a night and it costs about 12.16¢ a day, or $3.65 over 30 days.
GB: the MeacoFan 1056P on its top setting is 24 W. At 26.32p/kWh that is 0.63p an hour, 5.05p for an 8-hour night and £1.52 for 30 nights.
Getting more breeze for less
Point the fan at people, not the room; it cools skin, not air, so switch it off when you leave. On a hot night, a fan set low next to the bed is one of the cheapest comforts on the meter.
Questions
Is a fan cheaper to run than an air conditioner?
By a wide margin. A 24 W fan uses under a twentieth of the energy per hour of a typical window air conditioner.
Does standby matter?
Barely. The Meaco 1056P lists 0.9 W on standby and Hunter ceiling fans 0.3–0.4 W, which is small next to running power.
Why are no hours filled in?
No official usage figure exists for portable fans, so any number would be a guess. Use the quick hour buttons or type your own.