What Temperature Should I Have My Air Conditioner On?

Set your air conditioner to about 78°F (25–26°C) when you’re home and awake in summer, that’s the U.S. Department of Energy’s recommended balance of comfort and efficiency. Then nudge it higher when you don’t need full cooling: ENERGY STAR suggests raising the setting by about 4°F while you sleep and roughly 7°F while you’re away, which can trim around 10% off your cooling costs. Most people find a comfortable range somewhere between 73 and 79°F, and the right number for you depends on your personal comfort, the humidity, the climate where you live, and how well your home is insulated. The key isn’t chasing the coldest possible setting, it’s finding a steady, efficient temperature and adjusting it around your schedule. Below, we break down the best AC temperature for daytime, sleeping, being away, and saving energy, plus what to set window and portable units to.

What temperature should I have my air conditioner on? The factors to consider

There’s no single perfect number, but a few factors decide what works best for your home:

• Outdoor temperature. On very hot days you’ll want a lower setting; on mild days you may be comfortable higher, or with windows open and the AC off.
• Humidity. Damp air feels warmer, so you may need a slightly lower setting (or a dehumidifier) when humidity is high.
• Personal comfort. If you run warm or cold, adjust a few degrees to suit yourself, then leave it steady.
• Insulation and home size. A well-insulated home holds its temperature; a larger or leaky home may need a lower setting to stay even.

A good approach is to start around 78°F and adjust in small steps until you’re comfortable, rather than setting it very low and constantly fiddling with it. Once you find a setting that feels right, sticking with it is more comfortable and more efficient than frequent changes.

What should the AC be set at in summer?

The most common myth is that “as low as possible” is best. It isn’t, an extremely low setting wastes energy, strains the unit, and isn’t necessarily healthier. Keep these in mind when setting your AC in summer:

Consider the outdoor temperature: on a very hot day, set it lower; on a mildly warm day, you may not need it as low as you think. Factor in humidity, if the air is muggy, a slightly lower setting (or running a “dry” mode) compensates. And account for your own comfort, those who feel the heat may prefer a cooler setting, while others are fine higher.

For most homes, a daytime summer setting in the mid-to-high 70s works well, with 78°F as the efficiency-friendly baseline. When unsure, err slightly higher and let your comfort guide small adjustments.

What temperature to set the air conditioner in summer?

The ideal temperature for air conditioning in the summer

The ideal setting depends on the outdoor temperature, humidity, and how many people are in the space, but most people are comfortable between 73 and 79°F, with 78°F recommended for the best balance of comfort and energy savings while you’re home and awake.

You don’t have to hold one temperature all day. Raise it while you’re out to save energy, and lower it in the evening when outdoor temperatures fall and you want to wind down. A programmable or smart thermostat makes these shifts automatic, so you save without thinking about it.

What temperature to set the air conditioner in winter?

If your system also heats, a comfortable, efficient winter setting is around 68°F while you’re home and awake, lowering it when you sleep or leave keeps bills down. A programmable thermostat helps by adjusting automatically so you’re not heating an empty house.

Minimum outside temperature for an air conditioner

Standard air conditioners are built to cool, not to run in cold weather. Most are designed to operate efficiently when it’s roughly 60°F or warmer outside, which is why you don’t typically run a cooling-only AC in winter.

Running a standard AC well below its minimum outdoor temperature can reduce efficiency and risk damage, since the refrigerant and oil aren’t designed for those conditions. If you need cooling in cold weather (some server rooms, for instance), or you want year-round comfort from one system, ask an HVAC technician about equipment rated for low-temperature operation or a heat pump.

Best AC temperature for energy saving

For energy savings, 78°F is the sweet spot while you’re home and awake. It’s comfortable for most people and doesn’t overwork the unit. Setting it far lower wastes energy without a real comfort payoff.

The bigger savings come from adjusting around your day. The DOE notes you can save as much as 10% a year on cooling and heating by setting the temperature back 7 to 10°F for about 8 hours a day, for example, while you’re at work. So raise it when you leave, and let a programmable thermostat handle the schedule.

Pair the right setting with a few habits: close blinds or curtains to block solar heat, and run ceiling or box fans so you feel cooler at a higher thermostat setting. Fans let you raise the AC a few degrees without losing comfort.

What temperature should the air conditioner be set at night?

Many people sleep best in a slightly cooler room, and a common comfort range for sleeping is the mid-to-high 60s. From an energy standpoint, ENERGY STAR suggests raising the setting about 4°F above your daytime number while you sleep.

Those two ideas can both be true depending on your home and the outdoor temperature, what matters is finding a sleeping setting that’s comfortable for you without running the system harder than necessary. If you have health conditions that require a specific temperature, prioritize that. Otherwise, experiment a few degrees at a time to find your ideal sleeping setpoint.

How can you conserve energy with your air conditioner at night?

At night, lean on cooler outdoor air. When it’s mild, you can raise the AC setting or switch to fans and open windows to let cool air in. Set the thermostat fan to “AUTO” so the system only runs when it’s actually cooling rather than running the blower nonstop.

Keep the filter clean so the unit doesn’t work harder than it needs to, and use a programmable schedule to ease cooling overnight automatically. These small steps add up over a cooling season.

What temperature should I set my portable air conditioner?

A good rule of thumb is to set a portable air conditioner to about 78°F when you’re home and awake, the same comfort-and-efficiency balance that applies to central systems. Everyone’s preferences differ, so adjust a few degrees to find your sweet spot.

Humidity matters here too: in a damp space, a slightly lower setting (or a unit with a dehumidify mode) helps; in dry conditions, you can sit a few degrees higher and stay comfortable. And remember that portable units rely on proper venting, make sure the exhaust hose is connected and nothing blocks the vents, or the unit will struggle to cool no matter the setting.

AC temperature chart

A temperature chart is handy for knowing what to expect at different settings, and for spotting trouble. If your air conditioner is blowing warm air, comparing the actual output to what it should be helps you tell whether there’s a real problem.

As a quick reference using a home baseline: aim for roughly 78°F (about 25–26°C) for daytime comfort and efficiency, around 4°F higher while sleeping, and about 7°F higher while you’re away. A working central AC should also deliver air noticeably cooler than the return air, typically a meaningful temperature drop across the system. If your AC is set correctly but the air isn’t cold, the issue may be the unit or the thermostat, not the setting, and it’s worth investigating.

Window AC temperature setting

For a window unit, the same comfort target applies, around 78°F (roughly 24–26°C) when you’re home. If your window AC isn’t cooling, first make sure it isn’t accidentally set to a “heat” or “fan-only” mode, and that the temperature is set below the current room temperature.

Setting a window unit far too low just makes it run constantly and cost more without improving comfort. If it can’t keep up at a reasonable setting, check the basics: confirm vents aren’t blocked, clean the filter (a dirty filter restricts airflow), and make sure the unit is sized appropriately for the room. The owner’s manual lists the recommended settings for your specific model.

What temperature to set the air conditioner when away?

When you’re away for the day, raise the setting to save energy, ENERGY STAR suggests about 7°F above your normal setting, and the DOE often cites around 85°F for an empty home. This keeps the house from getting unbearably hot or humid while avoiding wasted cooling.

A few tips make the strategy work: make sure your home is reasonably well sealed and insulated so heat doesn’t pour in, keep blinds closed to block solar gain, and use a programmable or smart thermostat to cool the house back down shortly before you return. That way you save while you’re gone and walk into a comfortable home.

Is 72 a good temperature for air conditioning?

72°F is a comfortable, common setting, not too cold, not too warm, but it’s a few degrees below the 78°F efficiency baseline, so it will use more energy. Whether it’s “good” depends on your climate, your comfort, and your home.

In a hot, humid climate, some people prefer 72°F for comfort. In a large home, you may need a lower setting to keep every room even. But if energy savings matter, you’ll spend less by aiming closer to 78°F and using fans to stay comfortable. There’s nothing wrong with 72°F, just know it costs more than a higher setpoint. The size of your home and unit also influence how hard the system works to hold it.

Is 74 a good temperature for air conditioning?

74°F is a comfortable middle-ground setting that many people like, a touch cooler than the 78°F efficiency baseline but still reasonable. As with any setting, the best temperature is the one that keeps you comfortable, and a few degrees cooler or warmer is fine based on personal preference. If you want to trim energy use, nudging toward 78°F and running fans is the most cost-effective move.

Most comfortable AC temperature

The most comfortable AC temperature for most people falls between 72 and 78°F, but comfort isn’t only about the number on the thermostat, humidity plays a big role. Air that’s too humid feels warmer and stickier even at a cool setting.

For genuine comfort, aim to keep indoor relative humidity between about 30 and 60 percent alongside your temperature setting. Individual preference and your home’s conditions matter too. And don’t overlook maintenance: regular cleaning and service keep the system running efficiently, which makes holding a comfortable, even temperature much easier.

What is the normal AC temp for a house?

A widely used default for a home air conditioner is 78°F, the setting recommended for a good balance of comfort and energy efficiency while you’re home and awake. It’s comfortable for most people and uses less energy than colder settings. That said, “normal” is flexible, set your AC to whatever temperature keeps your household comfortable, and adjust it up while you sleep or leave to save energy.

How humidity changes the temperature you should set

Temperature is only half of comfort, humidity is the other half. The same 78°F feels cool and pleasant at 40 percent relative humidity but warm and sticky at 65 percent. That’s because high humidity slows the evaporation of sweat from your skin, which is how your body sheds heat. When the air is damp, your body can’t cool itself as efficiently, so a perfectly reasonable thermostat setting can still feel uncomfortable.

This is why people in humid climates often reach for a lower setting than they really need. A smarter move is to attack the humidity directly. Use your system’s “dry” or “dehumidify” mode if it has one, set the thermostat fan to “AUTO” so condensed moisture drains outside instead of being blown back in, and run a dehumidifier in problem rooms. Once indoor humidity sits in the comfortable 30 to 60 percent range, you’ll often find that 78°F feels perfectly cool, and you save energy by not over-cooling to compensate for damp air.

How to stay comfortable at a higher thermostat setting

The trick to saving money without feeling hot is making a higher setting feel cooler. A few proven tactics do exactly that:

• Run ceiling and box fans. Moving air creates a wind-chill effect on your skin, letting you raise the thermostat about 4°F while feeling just as cool. Turn fans off in empty rooms, though, since they cool people, not spaces.
• Block solar heat gain. Close blinds, shades, or curtains on sun-facing windows during the day. Direct sunlight can add real heat to a room and make your AC work harder.
• Seal and insulate. Weatherstrip doors and windows and seal duct leaks so the cool air you pay for stays inside.
• Cook and shower smart. Use exhaust fans and, on the hottest days, cook with the stovetop or outdoors instead of the oven to avoid heating the house.
• Maintain the system. A clean filter and clean coils let the AC hit your setting faster and run less, which directly lowers bills.

Stack a few of these and a 78°F house feels as comfortable as a colder, costlier setting, which is the whole point of choosing a smart temperature rather than just a low one.

Programmable and smart thermostats: set it and forget it

The easiest way to capture the savings from adjusting your temperature around your day is to let a thermostat do it for you. A programmable thermostat lets you build a schedule, for example, 78°F while you’re home, 85°F during work hours, and a comfortable sleeping setting overnight, so the house cools back down right before you wake or return without running all day.

Smart thermostats go further. Many learn your habits, adjust automatically, and let you change the temperature from your phone, useful if your plans change and you want to delay cooling an empty house. Some use geofencing to ease off cooling when everyone leaves and resume before you get back. The payoff is real: by holding a sensible setpoint when you’re present and backing it off when you’re not, these devices help you hit the DOE’s roughly 10% savings without sacrificing comfort or thinking about it. If you’re still adjusting a manual thermostat by hand, upgrading is one of the simplest ways to lower a summer cooling bill.

Why setting your AC too low can backfire

It’s tempting to crank the thermostat way down on a hot day, but it rarely helps and often hurts. Your AC cools at the same rate regardless of how low you set the thermostat, setting it to 65°F doesn’t cool the house any faster than setting it to 75°F, it just makes the system run far longer to reach a colder target. That means higher bills and more wear on the compressor.

An extremely low setting also widens the gap between indoor and outdoor temperature, and the bigger that gap, the harder and longer your system works to maintain it. On top of that, very low settings can over-cool a home to the point of discomfort and can even contribute to coil freezing in some conditions. The efficient, comfortable path is a steady, moderate setting plus the fan-and-shade habits above, not the lowest number the thermostat will accept.

There’s also a comfort cost to extreme settings: stepping between a frigid house and hot outdoor air repeatedly can feel jarring, and rooms kept very cold often feel damp because the system cycles off before fully dehumidifying. A moderate, consistent temperature keeps your whole home, and your body, more comfortable across the day than swinging the thermostat low and back up.

Should everyone in the home agree on one setting?

Households rarely agree on a single perfect temperature, one person runs hot, another is always cold. Rather than fighting over the thermostat, settle on a reasonable shared baseline like 78°F and let individuals fine-tune their own comfort. Someone who feels warm can use a personal or ceiling fan to feel several degrees cooler, while someone who’s chilly can add a layer or move out of a draft.

Zoning is another option for larger homes. A zoned system with multiple thermostats lets you cool the occupied parts of the house to different temperatures, so bedrooms and living areas can each suit their occupants without over-cooling the whole home. For most families, though, a moderate shared setpoint plus fans is the simplest, most efficient peace treaty, comfortable for everyone and easy on the energy bill.

Frequently Asked Questions

What temperature should I set my AC at night?

Many people sleep best in a slightly cooler room, often the mid-to-high 60s. For efficiency, ENERGY STAR suggests raising the setting about 4°F above your daytime number while you sleep. Find a sleeping setpoint that’s comfortable for you without overworking the system.

Will the AC reduce my body temperature?

AC cools and dries the air around you, which helps you feel cooler and more comfortable, especially in heat and humidity. It lowers how hot you feel by improving your environment rather than changing your core body temperature directly.

What is the air conditioner’s minimum outside temperature?

Most standard air conditioners are designed to run efficiently when it’s about 60°F or warmer outside. Running a cooling-only unit much colder than that can hurt efficiency and risk damage, which is why ACs aren’t typically used in winter.

What’s the best AC temperature for saving energy?

About 78°F while you’re home and awake. Then raise it roughly 4°F while sleeping and about 7°F while away. The DOE notes setting back 7 to 10°F for 8 hours a day can save around 10% on cooling and heating.

Next Steps

For the best mix of comfort and savings, set your air conditioner to about 78°F while you’re home and awake, then raise it roughly 4°F while you sleep and about 7°F while you’re away. Use a programmable or smart thermostat so those shifts happen automatically.

Keep in mind humidity, climate, and your home’s insulation when fine-tuning, and lean on fans, closed blinds, and a clean filter to stay comfortable at a higher setting. Find a steady temperature that suits your household and let small, scheduled adjustments do the rest.