Enter your AC running cost and how many degrees you can raise the thermostat using fans to see the savings.
Ceiling fans cool people, not rooms — turn them off in unoccupied rooms, since a fan running with nobody there only adds electricity cost with no comfort benefit.
A ceiling fan doesn't lower room temperature — it creates a wind-chill effect on skin that makes a warmer room feel comfortable, letting you raise the thermostat several degrees without losing comfort. Since AC energy use scales roughly 3% per degree of setpoint, even a small fan-enabled increase can meaningfully cut your AC running cost once the fans' own modest power draw is subtracted.
3-5°F is a commonly cited comfortable range for most people with a ceiling fan running directly overhead, though individual comfort varies.
No — since fans cool people, not the air, running one in an empty room provides no benefit and only adds unnecessary electricity cost.