Home AppliancesAir Conditioner

How Long Should an Air Conditioner Run To Cool a House?

Young Woman Switching On Air Conditioner While Sitting In Armchair At Home

Air conditioners are a blessing on a warm summer day. However, running them for a long time can impact your electricity bill and the appliance’s efficiency.

Knowing the ideal duration an AC takes to cool a house is essential.

Keep in mind that there is no one set duration or number, as several factors contribute to the efficient performance of your air conditioner.

But still, you can roughly calculate the time for running the AC to cool your house and the bill accordingly.


A central AC requires 15-20 minutes to cool down a three to four-bedroom house. As mentioned above, it is just an average duration, and several factors add up to the performance of your air conditioner.

Some common ones are:

  • Size of the air conditioner
  • Outside temperature
  • State of your AC

Read further to learn how much time an AC requires to cool down the house. We will also be discussing several factors that play a role in enhancing your AC’s performance.

How Long Does an AC Require To Cool Down a House?

Young Man Lying Under Air Conditioner On Couch Using Tablet At Home

Ideally, your central AC requires 15-20 minutes to cool down the house.

If your device is running for more than 20 minutes and still unable to maintain the desired temperature, it indicates that you have a smaller size that is overworking.

Factors That Affect the Speed of Cooling

Regarding cooling, you can’t determine one size fits all time duration. The following factors also play a critical role:

1. The Outside Temperature

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The higher the outside temperature, the longer your AC will cool down. Even with good insulation, heat can transfer into your house, making your appliance work more to reach the desired temperature.

Running the AC during rainy or humid weather will make your AC work faster and cool down more quickly.

2. Size of the Air Conditioner

Technician Service Checking And Repairing Air Conditioner Indoors

Buying the right size of air conditioner for your home is essential because an oversized or undersized AC will never perform as desired.

If your AC is undersized, it will take longer to cool down. Constant working can affect its performance and also cause overheating.

Similarly, an oversized AC will cool down your temperature quickly. However, it will short cycle and won’t effectively decrease humidity from the room environment, making you feel hot and sticky.

3. The Thermostat Setting

A Person Cooling Down With Air Conditioner

Your thermostat setting is vital in determining the accurate duration for your AC to reach the desired temperature.

If you have set the thermostat at a relatively lower number, the AC will take longer to reach it.

4. The State of Your Air Conditioner

Male Technician Repairing Air Conditioner With Screwdriver

It is a simple fact that a well-maintained, regularly cleaned air conditioner will perform well than a neglected and dirty one. It is good to pay close attention to regular wear and tear and get it fixed before severe damage.

In a nutshell, the cleaner and more maintained the AC is; the better it will perform.

5. The Size of Your Home

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The average duration of cooling down your house is calculated based on the 2,200 sq ft house. If you have a bigger home, your AC will take longer to lower the temperature.

Your appliance can only work well if you choose the right size of AC according to the home size.

6. Insulation of Your Home

Detecting Heat Loss At The House With Infrared Thermal Camera

It is advisable to insulate your home to prevent hot and cold air from entering the house and vice versa.

If you do not have good insulation at home, the cool air from your AC can also seep outside the home, making your appliance work harder.

You can opt for internal wall insulation or a stud wall made with insulated material to protect your home.


It will take around 15-20 minutes to cool down the house if you have the perfect-sized AC in good condition. However, this is just an average number; several factors can enhance or decrease its performance.

The only way to get the most out of your AC is to keep it clean and always get the right size.

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