Fan or air conditioner: what they cost

On hot days the choice is between a fan, which draws a few tens of watts, and an air conditioner, which can draw hundreds or over a thousand. This calculator compares the cost of a season of use for both and tells you how many times more the air conditioner uses than the fan.

It works in any currency: enter the energy price from your bill.

How the calculation works

• Cost: power × hours per day × days of use, times the price per kWh, for each appliance.
• Air conditioner power: enter the average power drawn, not the maximum. Inverter models often run at partial load once the room has cooled.
• Ratio: how many times more the air conditioner uses than the fan.

What a fan costs

8 hours a day for 90 days, energy at 0.30 per kWh:

What an air conditioner costs

Same data:

An air conditioner typically costs ten to thirty times as much as a fan. A portable unit usually uses more than a split system for the same cooling.

They are not the same thing

A fan moves air and evaporates sweat: your skin cools, but the room temperature does not fall. An air conditioner cools and dehumidifies the air. That is why on very hot days a fan may not be enough, while on milder days it often is. Using a fan alongside the air conditioner lets you set a slightly higher temperature with the same comfort.

The reading bands

• Ratio below 5: a modest gap.
• 5 to 15: the air conditioner uses a lot more.
• 15 to 30: on milder days the fan saves a lot.
• 30 and above: using the air conditioner only when needed makes the difference.

Limits of the calculator

Real air conditioner consumption varies with outdoor temperature, insulation, the set temperature and the model's efficiency: average power must be estimated, or measured with a plug-in meter for portable units. The calculator does not include buying or maintaining the appliances. In intense heat, especially for older and vulnerable people, cooling can be a health matter as well as a cost.

Frequently asked questions

How much electricity does a fan use?

Very little: a 40 W fan on 8 hours a day for 90 days uses about 29 kWh, about 9 at 0.30 per kWh.

How much does an air conditioner use?

Much more: at an average of 900 W, 8 hours a day for 90 days is 648 kWh, about 194 at 0.30 per kWh.

How many times more does an air conditioner use?

Often ten to thirty times as much as a fan, depending on the models and use.

Does a fan cool the room?

No: it cools your skin by evaporating sweat, but does not lower the air temperature.

Is it worth using both together?

Often yes: with a fan on, you can set the air conditioner a few degrees higher with similar comfort, saving energy.

What power should I enter for the air conditioner?

The average power drawn in use, lower than the maximum, especially for inverter models.

Does a portable air conditioner use more?

Generally yes for the same cooling: it is less efficient than a split system.

Is it useful to leave a fan on in an empty room?

No: it cools people, not the room, so switch it off when you leave.

Does it work in any currency?

Yes. Enter the price per kWh in your currency.