By plugging some basic info about your AC unit and usage into a few simple formulas, you can calculate the cost of running AC.

Energy Efficiency Ratio (EER) Formula

An AC unit’s Energy Efficiency Ratio (EER) is a measure of how efficiently it uses electricity to cool a home at any given moment. You can calculate the EER of your unit by dividing its cooling output in British Thermal Units (BTUs) by the power it’s using in watts. You’ll find these numbers in the unit’s manual or printed directly on the unit. Here’s the formula:

EER = unit BTUs / Watts consumed

Seasonal Energy Efficiency Ratio (SEER) Formula

Like EER, an AC unit’s Seasonal Energy Efficiency Ratio (SEER) rating is another measure of its efficiency. However, you’ll see SEER ratings are more common than EER and are often advertised by the manufacturers of AC units. This is because SEER ratings provide a broader picture of a unit’s efficiency, taking into account its performance over the entire cooling season.

Calculate your unit’s SEER rating by dividing its total cooling output in BTUs over a season by its total energy consumption in watt hours (Wh) over the same period. Here’s the formula:

SEER = unit BTUs / Wh consumed

Cost per Hour Formula (Most Popular)

To calculate the cost to run an air conditioner for one hour, consider the unit’s wattage, the average cost of electricity in your state and the number of hours your unit runs daily. Here’s the formula:

Cost per hour = (unit wattage x average cost per kWh) / 1,000

Note: These formulas provide estimates and may not reflect the exact cost of running your air conditioning unit. Actual prices can vary depending on various factors, including the size of your home, the temperature outside and your usage habits.

Using the formula above, you can calculate the cost of running your air conditioner per hour with data from your energy bill.

For example, the average price of electricity in the U.S. was about $0.15 per kWh as of August 2023 according to the U.S. Energy Information Administration. Assuming a typical AC unit with a wattage of 1,500, the calculation would be (1,500W x $0.15) / 1,000 = $0.23 per hour. The cost to run the same AC unit may vary depending on energy prices where you live.

Per Month Costs

You can use a similar formula to estimate the monthly cost to run your AC:

Cost per month = (unit wattage x hours of use per day x days of use per month x cost per kWh) / 1,000

Using the same figures from the example above, the calculation would be (1,500W x 8 hours x 30 days x $0.15) / 1,000 = $54 per month.

Per Year Costs

To estimate how much it costs per year for you to run your AC, use this formula:

Cost per year = (unit wattage x hours of use per day x days of use per year x cost per kWh) / 1,000

Using the same figures again, the calculation would be (1,500W x 8 hours x 180 days x $0.15) / 1,000 = $324 per year. This calculation accounts for six months of use each year, but households in some areas may use their ACs more or less often.

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What's the Cost of Running an Air Conditioner & Its Energy Usage?

Air conditioners and HVAC systems are the most electricity-demanding appliances in your home. That means they're also probably the most expensive item on your energy bill every month. But they don't have to be! Chances are, you could be paying less to cool your home.

The first step to saving is understanding your air conditioner's energy consumption and cost. Our AC cost calculator below can help you get an estimate of how much it will cost to run your AC unit per hour. Once you know how much it costs to run your AC, check out some of our tips and tricks to help you reduce your usage and save on your monthly costs.

Air conditioner energy cost calculator

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Terminology explained

Energy language can be confusing. Below, we break down what you need to know to use our calculator.

What are watts?

Watts measures the rate at which electricity moves through an appliance. More Watts means more electricity, which in AC terms means more cooling power. There are a few ways to calculate the Watts of your AC. To get the most accurate number, check the back of your AC unit. Most newer units will have the Watts written right on the back. The price of electricity is measured in kilowatts, so you'll have to divide that number by 1000 to get kilowatts.

If you can't find the Watts, look for measurements like BTU, SEER rating, amps, and volts. Depending on what numbers you find, you can calculate Watts via the following equations:

Kilowatts = (Amps x Volts) / 1000

Kilowatts = (BTU / SEER rating) / 1000

What is the average cost of electricity in the U.S.?

According to US Energy Information Administration, the average cost of electricity in the U.S. is 16 ¢/kWh. However, this number can vary depending on your electricity supplier. Today, people in some states have the power to shop for their electricity and find cheaper rates.

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What is the average cost and energy use of different types of AC units?

Central air conditioner

Size

BTUs

Watts

Cost Per Hour

Average Monthly Cost

Small

10,000 BTU

3,000 W

$0.480

$72.00

Medium

14,000 BTU

4,000 W

$0.640

$96.00

Large

18,000 BTU

5,000 W

$0.800

$120.00

*assuming that the electricity rate is 16 ¢/kWh and the AC is on for 5 hours per day

Window unit air conditioner

Size

BTUs

Watts

Cost Per Hour

Average Monthly Cost

Small

5,000 BTU

550 W

$0.088

$13.20

Medium

7,000 BTU

650 W

$0.104

$15.60

Large

10,000 BTU

900 W

$0.144

$21.60

*assuming that the electricity rate is 16 ¢/kWh and the AC is on for 5 hours per day

Mini split air conditioner

Size

BTUs

Watts

Cost Per Hour

Average Monthly Cost

1 Ton

12,000 BTU

1,500 W

$0.240

$36.00

2 Ton

24,000 BTU

6,000 W

$0.960

$144.00

3 Ton

36,000 BTU

9,000 W

$1.440

$216.00

*assuming that the electricity rate is 16 ¢/kWh and the AC is on for 5 hours per day

How to save on my air conditioner costs?

• 1 .

  Invest in a smart thermostat

  Smart thermostats use a combination of scheduling, motion-sensing, and geofencing to optimize heating and cooling in your home. A smart thermostat will automatically turn on and off your central heating and cooling systems according to your daily activity, minimizing electricity usage when you're not around. While investing in a smart thermostat requires an upfront cost, most smart thermostats report helping homeowners reduce their heating and cooling costs by 10-15%.

• 2 .

  Buy ENERGY STAR rated AC units

  The ENERGY STAR program was created by the Environmental Protection Agency (EPA) and the Department of Energy (DoE) to promote energy efficiency. The program intends to provide consumers with the information they need to purchase more efficient appliances for their homes. ENERGY STAR AC units are regarded as the most efficient products on the market, enabling consumers to lower their electric bills and carbon footprints. In 2019, ENERGY STAR products reportedly saved Americans $39 billion in energy costs.

• In 2019, ENERGY STAR products reportedly saved Americans $39 billion in energy costs.

• 3 .

  Ensure your home is well insulated

  The EPA estimates that homeowners can save 15% on their heating and cooling costs with proper insulation in attics, windows, and basements.

• 4 .

  Invest in a good fan

  The average AC unit uses 5-10x as much electricity as the average fan. Use a fan when you can to cut the cost of running your AC.

• 5 .

  Keep your windows closed

  Don't let your AC unit work in vain. Close those windows to maximize the effectiveness of your AC.

• 6 .

  Keep your windows closed

  Clean AC filters will help reduce how hard your AC must work to cool your home. The Department of Energy reports that regularly cleaning your filters can save you up to 15% on your monthly electricity spend on running your AC.

• 7 .

  Choose Perch Energy

  
  
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  • With Perch, you can take your fossil-fuel-fighting, money-saving ways even further when you also switch your home or business' electricity plan to cleaner energy. If you're on your utility's default basic service rate, it's a "mixed" energy plan (generated partly by fossil fuels, partly by renewable resources). But Perch can switch you to a low-cost cleaner energy plan—outside of what your utility is offering—that's backed 100% by clean, renewable resources like solar and wind. We'll find you a price that's lower than the market rate for similar options in your area. You don't have to do anything differently, but you'll feel great knowing that your personal electricity usage is now contributing to a healthier planet, and you've reduced your everyday carbon footprint.

  At Perch , we're on a mission to make cleaner energy more accessible, more affordable, and more equitable for all. Whether you rent an apartment, own a home, or run a business, Perch offers multiple ways to save money on your electricity bills, or even help the planet, too.

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