What is the ideal temperature to run an AC?

Author: Josefa Koss  |  Last update: Monday, September 29, 2025

According to the Department of Energy1, 78° Fahrenheit is the sweet spot for air conditioners to balance energy savings and comfort when people are at home and need cooling.

Is 72 a good temperature for air conditioning?

This is more of a personal question, as different people feel comfortable at different temperatures. Since 72 degrees is generally agreed upon to be an ideal indoor temperature, most people would probably still feel comfortable setting their AC units slightly higher than this, perhaps at around 75.

What should I set my AC to in summer?

What is the Best Thermostat Setting for Summer Air Conditioner Use? Energy Star recommends the following thermostat temperatures for your air conditioner in the summer: 78°F during the day if people are home. 82°F at night if people are home.

Does keeping the AC at 72 save money?

Best AC Temperature Settings While You Are Home

As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.

How cool should my house be if it's 100 outside?

When temperatures exceed 100 degrees Fahrenheit outside, setting your air conditioning (AC) to around 75-78 degrees Fahrenheit is generally considered efficient. Here are some reasons for this recommendation:

How to Run Your Air Conditioner in Summer and Winter | 2024 Update

How cool should my house be if it's 110 outside in summer?

For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.

What should I set my AC to on a 100 degree day?

For the most efficient performance, set the thermostat 20 degrees lower than the temperature outside. On a 100℉ day, set it to 78℉ to 80℉ to manage utility costs. If there's a lack of airflow, the filter may need to be changed or AC vents cleaned. But it may also mean your air conditioner needs professional repair.

What is the cheapest temperature to keep AC on?

Finding the right AC temperature for your electricity bill is a balancing act. By setting it around 78°F and considering external factors, you can enjoy comfort and save on energy costs simultaneously. Remember, small adjustments can lead to significant savings over time.

Is it better to run AC all day or just at night?

leaving it on all day and night is better for the HVAC system because it's less taxing. Should you turn off your AC when on vacation? HVAC experts agree it's better to keep your AC on when you're on vacation, especially if you don't plan to leave any windows open.

Is it expensive to leave the AC on all day?

Leave Your Air Conditioner On

You might think you're saving money by turning your AC off when you step out of the house. However, a wave of heat and humidity can sneak into your home in the interim. Therefore, leaving your air conditioner on all day in hot temperatures is more energy efficient.

Is it OK for AC to run constantly in summer?

Here's the thing: It's normal for your AC to run continuously during hot summer months. You see, on extremely hot days—we're talkin' high 90s to 100s—your system needs to keep up with the incoming heat. To do that, it will run longer in order to maintain a constant, desired temperature in your home.

What AC temperature is good for sleeping?

Sleeping in a room with the air conditioner set to an appropriate temperature is important for quality sleep. The ideal AC temperature for sleeping is around 65°F (18.3°C). However, this may differ between individuals, who might find their ideal AC temperature lies between 60 and 67°F (15.6 and 19.4°C).

Should AC be on auto or on?

There are benefits to having your air conditioner set to “auto” and “on.” The benefits of the “auto” setting include higher efficiency, lower energy bills, better humidity control, less wear and tear on some components, and quieter running.

Why not set the thermostat at 72?

Setting the thermostat below 72 degrees while using an air conditioner can cause the unit to work harder than necessary, leading to higher energy bills and potential damage to the appliance.

What is the best setting for AC in summer?

WHAT IS THE BEST MODE FOR AC IN SUMMER? In summer, the best mode for your air conditioner is the "Cool" mode, set to a comfortable temperature around 78°F when you're home. This setting efficiently reduces indoor humidity and maintains a comfortable environment without overworking the AC system.

What AC temp is too low?

A common rule of thumb is that most models can function properly only above 68 degrees Fahrenheit. Any lower temperature will result in the system freezing up. In addition to a frosty refrigerant, the piping and coils could also become covered with ice.

Is it better to turn off AC or raise temperature?

As it turns out, the most efficient way to keep your home cool and the bills low is to leave the AC running—ideally, with the temperature turned up toward the upper 70s.

What is the most cost-effective way to use air conditioning?

Increase the thermostat

If you are just as comfortable with your thermostat one or two degrees higher than you currently have it set, go ahead and turn it up. Even a one degree difference will have an impact on your energy bill. Many recommend 78 degrees as a good temperature for air conditioners to run efficiently.

Is it okay to leave the AC on 24/7?

Consequences of Running Your Air Conditioner 24 Hours a Day

Wasted energy: Running the AC to cool your home beyond your comfort level wastes energy and contributes to an increased carbon footprint. This is bad news for the environment and your energy bills.

What is the best temperature for AC to lower bill?

A more moderate setting like 24°C (75.2°F) can achieve comfort with reduced electricity usage.

What should I keep my AC on to lower my bill?

Set the thermostat as high as comfortably possible during hot weather. The less difference between the indoor and outdoor temperatures, the lower your cooling bill will be. Keep your house warmer when you aren't home during the day, but cooler when you come home at night.

Which AC mode to use in summer?

When you activate dry mode, the fan on your AC is set to a higher speed, which helps circulate and draw moisture out of the air. Dry mode is especially useful during humid seasons such as summertime, when you may find yourself fighting against high levels of humidity in your home.

How cool should my house be if it's 90 outside?

What should my AC be set at if it's 90 degrees outside? If the outdoor temperature is 90 degrees, it's recommended to set your thermostat between 75-78 degrees.

What is the best thermostat schedule for summer?

Keeping in mind both energy efficiency and comfort, the best thermostat settings for summer are 76° when you are home, 80-85° when you are away and 72° at night. Then use ceiling fans in the rooms you are in to feel up to 4* cooler. Here's more on why these thermostat settings are the best.

How many hours should AC run per day?

On an average summer day, a general guideline is that your AC should operate between 12 and 16 hours. However, several factors can influence this, including the outdoor temperature, desired indoor temperature, the size and type of your unit, and your home's energy efficiency.

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