What is the lowest you should set your AC to?

Author: Edna Gerhold  |  Last update: Thursday, October 23, 2025

In short, the 20-degree rule of air conditioning states that you should always keep your AC unit at no more than 20 degrees lower than the outside temperature. It means that, if the outdoor conditions are at 95 degrees, you should set your thermostat at no less than 75 degrees.

What is the lowest an AC should be set at?

70°F is an ideal temperature setting, regardless of how hot it gets outside. This is a comfortable temperature for most, though you may find that it can feel too cold at times. Any air conditioner set lower than this is at risk of having its coil freeze.

Is 72 a good temperature for air conditioning?

Setting your air conditioning to 72°F is generally considered a comfortable indoor temperature for many people. It strikes a good balance between comfort and energy efficiency, making it a popular choice for residential settings.

Is 70 too low for AC?

If you want to feel good, as in comfortable, many people will want to lower their thermostat to the low 70s in summer. But if you're talking about saving money on energy and limiting your environmental impact, 70 degrees Fahrenheit is a very bad temperature for your AC to reach.

Is 67 too low for AC?

When the AC temperature is too low, between 60-67 degrees F (15-19 degrees C), the evaporator coil inside the unit can get excessively cold. If the humidity in the room is high, condensation can accumulate on the coil, which may lead to the formation of frost or ice.

Best AC Setting For Cooling: Best Air Conditioner Temperature to Save Money, Set AC to Auto or On?

Is 68 too cold for AC in summer?

Set a reasonable temperature: HVAC professionals strongly recommend never setting the thermostat lower than 68 degrees in the summer. To balance comfort and energy efficiency, the Environmental Protection Agency recommends setting your thermostat to 78 degrees when you're at home and awake.

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.

What should I set my AC to at night?

Recommended AC Temperature for Sleeping

The Sleep Foundation says 65° is the best temperature for sleeping. However, if you prefer a slightly warmer or cooler room, that's okay, too. The recommended range is 60–68°, so there is some wiggle room.

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 110 outside?

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.

Why is my AC set to 72 but reads 78?

Clean the Thermostat

Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.

What is the safest temperature for AC?

Hence, to take a temperature closer to 24 degrees is considered to be healthier for individuals in tropical regions like India. The ministry says that, as per the comfort chart, temperatures up to 25 degrees are quite comfortable for human body, along with the desired humidity and air movement values.

What is the best temperature for sleep?

The best room temperature for sleep is approximately 65 degrees Fahrenheit (18.3 degrees Celsius). This may vary by a few degrees from person to person, but most doctors recommend keeping the thermostat set between 65 to 68 degrees Fahrenheit (15.6 to 20 degrees Celsius) for the most comfortable sleep.

What is the lowest I can run my AC?

HVAC manufacturers typically advise users not to run their units for extended periods if the temperature is below 65 degrees Fahrenheit. If you need to test your unit, you should do so after the weather has been risen to 60 degrees Fahrenheit for at least three days.

What is the lowest point of AC?

The minimum point of AC curve falls towards right of AVC curve because AC continue to fall even after AVC starts rising because AFC falls.

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.

Is 73 too low for AC?

To maintain a comfortable indoor environment during the summer, the American Society of Heating, Refrigerating & Air Conditioning Engineers recommends a range of 73 to 79 degrees Fahrenheit. On scorching hot days, you may want to adjust your thermostat toward the higher end of that range.

What is the cheapest temperature setting for AC?

One great way to lower energy costs is to avoid cooling an empty house. This is especially true during the middle of the day. If everyone in your household is either at work or school, then turning the temperature to 78-80 degrees will save you a chunk of change when the energy bill arrives.

Is 72 for AC too cold?

When setting your thermostat, most homeowners find 72 is a good temperature for air conditioning. However, you may need to adjust that setting based on weather conditions. The bigger the difference between indoor and outdoor temperatures, the higher your energy bill will be.

Is it OK to run AC all night?

Running the “auto” function of your air conditioner all day and night isn't the best idea for any home. There are a few reasons you don't want to run your AC system all the time: System stress: Your air conditioner unit needs time to take a break.

What should you set your AC to in summer?

According to ENERGY STAR, a division of the U.S. Environmental Protection Agency, 78 degrees Fahrenheit is the most cost-effective AC setting during the summer months. 1 And that's just the recommendation for when you're at home.

Is 78 too hot for a house?

Quick answer: The ideal house temperature is room temperature, which ranges from 68 to 78 degrees F, though this may vary from season to season. In winter, the average room temperature is generally 62 to 68 degrees, whereas in the summer, the average temperature is 72 to 78 degrees.

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 is the coolest number for AC?

Setting your AC to 16°C will cool the room more than setting it to 30°C. However, keep in mind that extremely low temperatures can lead to higher energy consumption and may not be comfortable for occupants. A moderate setting, like around 22–24°C, is often recommended for both comfort and efficiency.

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).

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