How much electricity (kWh and kW) does an air conditioner use?

Air conditioners are an essential appliance, particularly in areas with extreme temperatures. However, their high energy consumption is a cause for concern, especially for those looking to save on electricity bills or transition to independent sources of energy.

But how much electricity does an air conditioner use exactly?

Well, there are a few units of measurement that quantify each aspect of electricity, such as Amps, Volts, Watts, etc…

However, the most important aspect of electricity, and what you actually pay for at the end of the month, is “Electrical Energy”, which is measured in “kWh (kiloWatt-hours)”.

So, a better question to ask would be: How many kWh does an air conditioner use?

In this article, I’ll explore the Energy consumption of air conditioners, and how to measure their kWh usage, and I’ll provide estimates of the cost to run them based on their BTU ratings or tonnage.

Once we’ve established how much Electrical Energy (kWh) it takes to run your air conditioner, I’ll also discuss its Electrical Power (kW) requirements, which will be pretty informative if you’re planning on running your air conditioner on solar power, batteries, or other alternative sources of energy in general.

Let’s dive in.

How many kWh does an air conditioner use?

The energy consumption of an air conditioner, or the amount of kiloWatt-hours (kWh) that it uses, depends on several factors, including:

• The capacity of the air conditioner, rated in BTUs (British Thermal Units) or Tons
• The efficiency of the air conditioner
• The usage duration
• The outdoor temperature
• The quality of the insulation

While these variables make it challenging to provide an exact answer as to how much energy your air conditioner uses, to put things into perspective, the following table provides estimates of the hourly energy usage of air conditioners based on their BTU ratings:

These estimates provide a general idea of the hourly energy consumption of air conditioners based on their capacity.

For example, a 5000 BTU (Window) air conditioner uses – on average – between 0.25 and 0.4 kWh of energy per hour of use. If a 5000 BTU air conditioner is left on for 8 hours a day, it would use between 60 and 100 kWh of energy each month.

In comparison, a 36000 BTU (3 Ton) central air conditioner uses – on average – between 1.5 and 2.8 kWh of energy per hour. If an air conditioner of this size is left on for 8 hours a day, it would use between 360 and 650 kWh of energy each month.

Again, keep in mind that several factors influence an air conditioner’s energy consumption, and these estimates are intended to provide a general perspective. To determine the kWh usage of your AC as accurately as possible, I recommend measuring it.

How to measure the energy consumption of your air conditioner?

Measuring the energy consumption of your air conditioner is crucial to managing your electricity usage and reducing your bills. Fortunately, there are several tools available to help you measure your air conditioner’s energy consumption accurately.

One option is to use an electricity monitoring device like the Kill-A-Watt meter. This device is easy to use and connects to your air conditioner’s wall outlet or inverter.

All you’ll have to do is plug your air conditioner into the Kill-A-Watt meter, and it will measure the exact amount of energy that your air conditioner consumes over a certain period.

If, for example, you’d like to measure your air conditioner’s monthly energy consumption, you could plug your AC unit into the Kill-A-Watt meter, and check the “kWh” readings 24 hours later.

By doing this, you’d be able to measure the daily energy consumption of your air conditioner, which you can then multiply by 30 to determine its monthly energy usage.

For example, the following video shows a 5000 BTU window air conditioner that consumed 1.6 kWh of energy over 3 hours and 30 minutes.

If you have a central air conditioner that operates at 220 Volts and runs on a dedicated circuit, you can use the Emporia monitor.

This device is installed in your main electrical panel and sends real-time data to a monitoring app on your phone or tablet. However, please note that you may need to hire an electrician to set up the device for you.

In any case, the following video explains how the Emporia monitor works:

Alternatively, if you don’t want to purchase an electricity monitoring device, you can use our Appliance Energy Consumption Calculator to estimate your air conditioner’s energy usage. However, please note that the calculator will only provide estimates and might not be as accurate as using an electricity monitoring device.

Now that we’ve looked at how to measure the energy consumption of your air conditioner, or at least how to estimate it, let’s explore the costs associated with this energy consumption.

How much does it cost to run an air conditioner?

The cost to operate an air conditioner is mainly determined by three factors:

• The rate at which the air conditioner consumes energy (e.g., an energy consumption rate of 1.5 kWh per hour)
• The frequency or the duration of the usage (e.g., 8 hours per day)
• And the cost per kWh in your location (e.g., 20 cents per kWh).

To provide some perspective, the following table categorizes air conditioners by size (BTU rating or tonnage), and provides some estimates of how much it would cost to run each of them for 1 hour:

Please note that the estimated running costs provided in the table are based on the February 2023 data from the EIA (U.S. Energy Information Administration).

For example, if a 24000 BTU (2 Ton) central air conditioner is left on for 8 hours a day, it would – on average – cost between $38 and $72 per month to run the air conditioner.

However, please note that the estimates provided in the table are based on the (U.S.) national average cost per kWh. The actual cost per kWh differs from state to state.

To get more accurate estimates, I recommend measuring the actual energy consumption of your air conditioner (as explained above), and factoring in the electricity costs specific to your location:

Monthly Cost To Run Your Air Conditioner (Cents) = Monthly Energy Consumption Of Your Air Conditioner (kWh) x Electricity Costs In Your Area

For example, let’s say you’d like to estimate the monthly cost to run a 12000 BTU AC. Let’s also assume the following:

• You’ve monitored the energy consumption of the air conditioner over a 24-hour period and determined that it uses 6.4 kWh per day:
• You live in the state of Kansas

The monthly energy consumption of the air conditioner can be calculated as such:

Monthly Energy Consumption (kWh) = Daily Energy Consumption (kWh/day) x 30 days

Monthly Energy Consumption (kWh) = 6.4 kWh/day x 30 days

Monthly Energy Consumption (kWh) = 192 kWh/month

According to the February 2023 data from the EIA, 1 kWh of energy costs 14.71 Cents in Kansas. The monthly cost to run the air conditioner can be estimated as such:

Monthly Cost To Run Your Air Conditioner (Cents) = Monthly Energy Consumption Of Your Air Conditioner (kWh) x Electricity Costs In Your Area

Monthly Cost To Run Your Air Conditioner (Cents) = 192 kWh x 14.71 Cents/kWh

Monthly Cost To Run Your Air Conditioner (Cents) = 2824 Cents

Monthly Cost To Run Your Air Conditioner ($) = 28.24 $/month

If you don’t have an electricity monitoring device and are not planning on using one anytime soon, you can use the following calculator which will estimate the cost of running your air conditioner based on its type, size, and the area that you live in:

Now that we’ve covered the cost of running an air conditioner, let’s dive into another important factor: how much power (kW) it uses.”

Now that we’ve covered the energy consumption (kWh) of your air conditioner, and how much it costs to run it, let’s discuss other electrical specifications that may be relevant if you’re looking to power your AC with alternative energy sources.

How much power (kW) does an air conditioner use?

While Wh (Watt-hours) and kWh (kiloWatt-hours) measure the amount of Energy that an air conditioner consumes over a certain period of time, W (Watts) and kW (kiloWatts) measure the amount of Power that the AC uses at a given moment.

Learn more about the difference here: kW vs kWh

The power usage of your AC unit, or its Wattage, is very important when trying to size a generator or an inverter that could run your air conditioner.

So, how many watts does an air conditioner use?

The amount of power that an air conditioner uses depends on its BTU (British Thermal Units) rating, the higher the BTU rating, the more power the AC uses. For example, while a 24000 BTU (2-ton) air conditioner uses around 2000 watts, a 36000 BTU (3-ton) AC unit uses around 3000 watts.

It’s also important to note that newer air conditioners are significantly more efficient, meaning they use less power and energy to run at the same capacity. This “efficiency” is indicated by a SEER or EER rating (12 EER for example).

This efficiency can actually be used to calculate the specific power usage of your unit. But before I explain how that goes, here’s a table that gives you an idea about the power usage of air conditioners based on their capacity:

Please note that these figures are still just estimates. You can, however, use the information provided by the manufacturer to determine the power usage of your air conditioner.

Generally, there are a couple of ways to do this:

1- Use the Capacity and Energy Efficiency Ratio (EER) of your air conditioner:

Air conditioners will usually have an Energy Efficiency Ratio (EER) rating, and this rating can be used to estimate the power usage of the unit:

Power Usage (Watts) = BTU Rating ÷ EER

Both of these ratings are usually provided within the EnergyGuide label that comes with your AC. For example, the following label is for a 10000 BTU air conditioner that has an EER of 11:

The power usage of this air conditioner can be calculated as such:

Power Usage (Watts) = BTU Rating ÷ EER

Power Usage (Watts) = 10000 BTUs ÷ 11

Power Usage (Watts) = 909.1 Watts

Some EnergyGuide labels only provide a Seasonal Energy Efficiency Ratio (SEER) rating, which is not the same as and should not be confused with the EER rating of your air conditioner.

In this case, you can use the following formula (provided by the U.S. DOE) to calculate the EER rating of your AC unit:

EER = (1.12 × SEER) – (0.02 × SEER²)

For example, if you have a 12000 BTU air conditioner, and the yellow label specifies a SEER rating of 22, its EER rating can be calculated as such:

EER = (1.12 × SEER) – (0.02 × SEER²)

EER = (1.12 × 22) – (0.02 × 22²)

EER = 14.96

The power usage of this AC is:

Power Usage (Watts) = BTU Rating ÷ EER

Power Usage (Watts) = 12000 BTUs ÷ 14.96

Power Usage (Watts) = 802.14 Watts

In case you can’t find the EnergyGuide label, you can still use the electrical specifications of your air conditioner.

2- Use the Voltage and Amperage specified on your air conditioner:

As previously mentioned, the power usage of an appliance can be calculated using its voltage and amperage:

Power (Watts) = Voltage (Volts) x Amperage (Amps)

While most appliances in the U.S. (including small air conditioners) operate at 120 Volts, large central air conditioners require 240 Volts to operate.

The amperage of the unit will depend on its capacity and efficiency, and will usually be specified under Amps, Current, or RLA (Rated Load Amps) for bigger air conditioners.

These specs can be found in the technical specification sticker, which is usually stuck somewhere on the AC unit.

For example, here’s a specification label for a 5000 BTU unit:

This particular specification label provides the wattage of the unit, which is pretty useful. But in case it didn’t, the wattage can still be calculated as such:

Power (Watts) = Voltage (Volts) x Amperage (Amps)

Power (Watts) = 115 Volts x 4 Amps

Power (Watts) = 460 Watts

Here’s another example of a much bigger AC unit, where the wattage is not directly specified:

The image above shows the technical specifications of a 36000 BTU central air conditioner. The Rated Load Amps for this AC unit is 14.4 Amps and its voltage says 208/230V, which means that its voltage is 240 Volts.

As a general rule of thumb, the power usage of this air conditioner can be calculated as such:

Power (Watts) = Voltage (Volts) x Amperage (Amps)

Power (Watts) = 240 Volts x 14.4 Amps

Power (Watts) = 3456 Watts

The actual power usage of this particular unit will be lower than 3456 watts (because of its power factor), however, overestimating is better than underestimating in this case.

In any case, it is also important to note that when choosing an inverter that can your air conditioner, the surge power that your AC unit requires to start should also be taken into consideration. Click here to learn more about this topic.

Frequently Asked Questions:

How many kWh does a window ac use?

As a rule of thumb, and depending on its size, ambient temperatures, and the quality of insulation, a window air conditioner will use between 0.25 and 1 kWh (kiloWatt-hours) of energy per hour of use.

For example, a small 5000 BTU window air conditioner will use around 0.35 kWh of energy per hour. Assuming 8 hours of daily use, the energy consumption of a unit of this size accumulates to about 80 kWh of monthly energy usage.

In comparison, a 12000 BTU window air conditioner will use around 1 kWh of energy per hour. Assuming 8 hours of daily use, the energy consumption of an AC unit of this size amounts to around 250 kWh per month.

How many kWh does a 2-ton central ac use?

On average, a 2-ton (24000 BTU) AC unit will use around 1.5 kWh of energy per hour of use. Assuming it is left on for 8 hours a day, a 2-ton air conditioner will consume around 12 kWh of energy on a daily basis, which equates to about 360 kWh of energy per month.

According to February 2023 data, it would cost between $40 and $80 per month to run a 2-ton AC unit.

How many kWh does a 3-ton central ac use?

On average, a 3-ton (36000 BTU) AC unit will use around 2.5 kWh of energy per hour of use. Assuming it is left on for 8 hours a day, a 3-ton air conditioner will use around 20 kWh of energy on a daily basis, which equates to about 600 kWh of energy per month.

According to February 2023 data, it would cost between $70 and $120 per month to run a 3-ton AC unit.

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