How Much Electricity Does an AC Use? (The BEST Answer!)

Are you looking to budget your electricity use to save money? Or maybe you’d like to cut back on electricity to benefit your environment? Perhaps you’re just curious?

Whatever the reason might be, knowing how much electricity your AC uses is essential. So, we’ll show you how to calculate the exact power consumption of your AC.


Different factors affect the usage, so there’s no exact number. However, there is a simple formula that’ll help you estimate both the power consumption and cost.

By the end of this article, you can consider yourself an expert on all things electricity and ACs!

How Much Electricity Does an AC Use?

Now let’s get to the calculations! Luckily, you don’t need to be Einstein to be able to calculate your AC’s power consumption or estimated costs of that power. All you need are two set values:

-Your AC’s electricity consumption (which you can find on its energy-saving label)

-Your country’s or state’s tariff rate.

To calculate how much electricity your AC uses, all you need to do is multiply the electricity consumption (in watts or kilowatts) by the number of hours you used it for.

And to calculate the estimated costs, all you need to do is multiply the energy consumption by the tariff rate.

For example, if you used an AC that has electricity consumption of 400 watts per hour for 4 hours in a state that has a tariff rate of 0.1, the energy consumption will be 400 x 4 = 1600 watts, and the cost will be 1600 x 0.1 = 160 dollars.

This formula gives you only an estimate of the electricity consumption and costs, though, since there are factors that also affect the actual amount.

Aspects That Affect Power Usage of Your AC

As we mentioned before, several things affect the power usage of your AC. Some things affect it positively, while others; negatively. So, you’ll know how to control these variables to your benefit!

Number of People Using It

For an AC to be efficient, it should cool off the person in the room. An average person produces 100 watts of heat, so neutralizing that will need 100 watts of power from your AC (watts is the unit of power for electricity).

So, naturally, the more people in one room, the more electricity needed and the more expensive your electricity bill will be.

So, if you live in a crowded household, you can expect that more electricity will be used from your AC.


Unfortunately, your AC isn’t selective with what it cools. The cool air coming from the AC will spread to all the hot areas and objects in the room, whether it’s you or your cupboard.

So, when you leave a box or closet open, that increases the volume of the room since that’s extra heated space that needs to be cooled. That can be a waste of electricity.

Therefore, a good tip to avoid the waste of electricity and decrease your monthly bill is ensuring that all cupboards or closets are closed.

Size of the system

An AC works by replacing the hot air in an area of space with cold air instead. So, it’s implied that a bigger room will require more electricity to cool off. This relationship is linear, meaning it increases at a constant rate.

The way to calculate it is by multiplying the area by 10 to figure out the number of watts used. For example, an empty 100 sqft room will use 1000 watts of electricity from your AC to cool off.

So, if you’re looking to save on electricity, try using a smaller room to cool off!


If your room was previously cool, it’d take less power, therefore less electricity. It takes around 2 watts to cool off 1 Fahrenheit of heat.

For example, if your room was 90 Fahrenheit and it cooled down to 75 Fahrenheit, it took your AC around 30 watts of power to cool off the room.

On the other hand, if your room was 100 Fahrenheit and it cooled down to 75 Fahrenheit, it took your AC around 50 watts of power to cool off the room.

So, that’s why in warmer months, you’ll expect that your electricity consumption will be way higher!


As mentioned before, ACs cool everything in your room. So, when there are electrical appliances in your room, they’ll generally carry more heat because the heat comes from power, and power comes from electricity.

This means that a room with several electrical appliances will commonly use more power and electricity to cool off—making your electricity bill higher than usual.

So, next time you turn on your AC, move any useless appliances that might be in the room.

AC’s Efficiency Rating

One major factor that affects an AC’s power consumption is its efficiency rating—otherwise known as the Seasonal Energy Efficiency Ratio (SEER) rating.

SEER ratings judge how efficient your AC is in consuming power. Your AC doesn’t utilize all the energy it gets from electricity. Some of that energy is wasted on heat.

So, that’s why experts calculate the AC’s efficiency by dividing the cooling output per season over the number of watts used by the hour.

The bottom line of it is that the higher the rating, the more efficient your AC is. So, your AC will use less electricity to provide cool air.

The U.S. Department of Energy set regulations that allow the minimum rating to be 13.

However, ACs can reach as high as 25. Although ACs with higher ratings tend to be more expensive, it’s definitely worth it in the long run since you save more electricity and money.


Figuring out how much electricity your AC uses is a lot easier when you understand what takes up the electricity.

So, if you’re trying to cut back on bills or energy consumption, you’ll be pleased to find out how easy it actually is.