Air Conditioner vs Fan: Running Cost and When Each Is Worth It
Published: May 24, 2026
Before you weigh up air conditioners by cost per hour to run, it’s worth asking the cheaper question first: would a fan do? The honest answer comes down to two numbers and one piece of physics.
The running-cost gap
| Appliance | Typical power | Cost per hour (UK 24.5p/kWh) | Cost per hour (US 16¢/kWh) |
|---|---|---|---|
| Tower / pedestal fan | 40–70 W | ~1–1.7p | ~0.6–1.1¢ |
| Ceiling fan | 15–60 W | ~0.4–1.5p | ~0.2–1¢ |
| Portable air conditioner | 1,000–1,800 W | ~25–44p | ~16–29¢ |
| Mini-split (per hour cooling) | 500–1,200 W | ~12–29p | ~8–19¢ |
A fan costs roughly a twentieth to a fortieth of a portable air conditioner to run. Run a 50 W fan all night for pennies; run a 1.2 kW portable for the same 8 hours and it’s about £2.35 a night in the UK.
But a fan doesn’t cool the air
Here’s the physics that the cost table hides: a fan doesn’t lower the room temperature. It moves air across your skin, which speeds up sweat evaporation and makes you feel a few degrees cooler. The room stays the same temperature — in fact the motor adds a tiny bit of heat.
An air conditioner removes heat from the room and pumps it outside, so it actually drops the air temperature and (as a bonus) removes humidity. That’s what you’re paying 20–40× more per hour for.
How to decide
- A fan is enough when: the room is only a little warm (say up to ~28°C), the air is dry, and you mainly want a breeze. It’s by far the cheapest comfort per hour.
- You need an air conditioner when: the air itself is too hot for a breeze to help (a fan blowing 32°C air just moves hot air around), you need to sleep through a heatwave, the room is humid, or you want a reliably cool temperature rather than a wind-chill effect.
- Use both: running a fan alongside an AC lets you set the AC a degree or two higher for the same comfort — trimming the expensive part of the bill.
The bottom line
A fan wins on running cost by a mile, but it can’t cool hot or humid air. If a breeze does the job, save your money. If you need the temperature to actually come down, that’s what air conditioning is for — and the number that decides which unit is cost per hour to run.
Next: air conditioners ranked by cost to run · how much does an air conditioner cost to run? · running-cost calculator.
