What Size Central Air Conditioner Do I Need?

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Updated February 8, 2023

If you are new to the world of indoor cooling, you may want to learn what size central air conditioner to purchase for your home to take care of excess heat in the space. Calculating the square footage of the home is the first step when determining the size of the central air conditioner you need. You can do this by using an online calculator or talking to an HVAC professional. Moreover, you’ll want to measure a potential unit by checking out the specifications.

Some of the best air conditioners, after all, are central units, and these appliances ship in a wide array of tonnage sizes to suit different home layouts, from how many rooms you have, the insulation, how many windows there are, how many housemates you live with, etc. If you live in a very hot climate year-round, a central AC can be a great investment, but it’s important to get the sizing right since the wrong size can be ineffective and a waste of money and increase your energy bills.


  • Central air conditioning systems require around 1,000 BTUs to cool 100 to 150 square feet successfully.
  • Add up the square footage of your home and convert that to BTUs using the above formula, or use an online calculator.
  • Check out advertising materials for central air conditioners, as they should indicate the cooling capacity of the outdoor unit, in addition to listing energy costs.

How to Choose the Best Central AC Size

The size of an air conditioner depends largely on its cooling power and the overall dimensions of your home, which is why many people wonder what size air conditioner is perfect for 14×70 mobile homes. If you already have an air conditioner, just look at the BTU rating and replace it accordingly. You might want to look into energy-efficient models if you’re looking to save on your energy bills more.

However, if you don’t have a central system in place, you need to figure out your home’s size and answer some other questions, such as how big of a generator you need to run a 5000 BTU AC Unit.

Insider Tip

No matter what size you choose, remember to change out the air filters every two months or so, depending on usage.

Luckily, there are some fairly standard ways to pick a correctly sized AC unit for your home, so you can move on to learning where the contactor is located within your air conditioner.

Use an Online Calculator

There are plenty of calculators available online for just this purpose. These apps ask for some simple information, such as your home’s size in square footage, and come back with the perfect BTU rating for you. Once you have this information in hand, start shopping for a central air conditioner or full HVAC system. Many of the major AC manufacturers operate these calculation systems.

STAT: Having a little extra power from a slightly bigger size unit than you need isn’t bad. This will make sure your system can handle the load on days with extremely high or low temperatures. If you get a unit that’s too small, you may regret it on the hottest and coldest days of the year. (source)

Check Out AC Specs

Generally speaking, you’ll add 1,000 British Thermal Units (BTUs) for every 100 square feet included in your home. An extremely small home of 150 square feet requires 1,000 BTUs, for instance, while a larger home of 1,000 square feet requires 20,000 BTUs. When shopping for a central AC system, check out the specs. These specifications typically include the cooling power in BTUs, and some even include the maximum amount of physical space the AC can handle.

Talk to a Pro

As a last resort, simply call and talk to a professional AC installer. These pros will be more than happy to answer your questions about air conditioner sizes relating to home size. Have your home’s square footage available before making the call to find out the properly sized units faster on the call.

Central AC Size FAQs

How are central air conditioners measured?

Central air conditioning units are measured via British Thermal Units, otherwise known as BTUs. These units indicated the cooling power of a central air conditioning unit.

Why is it a bad idea to install the wrong size AC unit?

If you are looking for an energy-efficient model, install a correctly sized AC unit. Going with the wrong sized unit results in higher energy bills and decreased energy efficiency.

How to get the best air conditioner prices?

Check out online sales to find the right prices. In addition to the cost, the advertising. materials should also list the efficiency rating, the air conditioner size, and more.
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