cooling area of 3-ton AC unit

How Many Square Feet Does a 3-Ton Air Condition Cool?

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When shopping for an air conditioner, it’s important you pick a unit whose size is appropriate for your home. You may think the bigger the AC unit, the better — but that’s not the case. Today, we will discuss exactly how much area you can cool with a 3-ton air conditioner.

If the AC is too big for your home, it is likely to cool the space too quickly. As a result, its compressor will shut off and turn on continuously, which in turn reduces its efficiency and pushes the energy costs up.

In contrast, an AC unit that’s too small for your home will run constantly to cool the space — and sometime still may fail to achieve the desired temperature. This will bump up your energy costs and may even leave your home too warm during the summer months.  On the other hand, the right-sized AC unit can provide your family with optimal comfort without unnecessarily increasing energy costs.

So, how many square feet does a 3-ton air conditioner cool? A 3-ton air conditioner cools roughly 1,800 square feet. Of course, there are variables that come into play, such as how well your house is insulated and the style and number of windows. The above estimate is for a relatively well-insulated home with newer-style windows. Continue reading for more.

In the remainder of this article, we will take a detailed look at the variables that affect cooling and how you can pick the right air conditioning system for your home.

How many square feet will a 3 ton AC cool?

First, let’s find out how air conditioner sizes are measured. The cooling capacity of an air conditioning unit is determined in tons and is based on the amount of heat — measured in British Thermal Unit (BTU) — it can remove in an hour. A one-ton air conditioner can remove 12,000 BTU per hour. This means a three-ton air conditioning unit removes 36,000 BTU in an hour. 

As a rule of thumb, one tone is needed per 600 square feet for residential spaces. So, a 3-ton unit can condition about 1,800 square feet.

Why Does HVAC Size Matter?

Does size really matter? When it comes to your HVAC unit — HVAC stands for Heating, Ventilation, and Air Conditioning — the answer is a loud YES! Installing the right-size HVAC unit is essential for staying comfortable all year long.

Here are four reasons why it is important that you pick an air conditioning unit that’s of the right size for your home:

  1. Better Comfort

Ever walked into a house on a sultry afternoon only to find that, while the temperature inside is adequately cool, the air is sticky or muggy? Blame it on an improperly sized air conditioning system.

An air conditioner not only cools a home but also dehumidifies it, with the latter taking longer to achieve. If the HVAC unit is oversized, it will run short cycles and consequently will not be able to properly dehumidify the space.

  • Greater Efficiency

An undersized HVAC system will need to run continuously to sufficiently cool the home. This, in turn, will increase your energy bills. You might think that a large air conditioning system will be more efficient, but that’s not true. If the HVAC is too big for your home, it will constantly turn off and on, raising the utility cost in return.

Therefore, short cycling with a big HVAC system is just as bad for your pocket as running continuously with a unit that’s too small for your space.

  • Reduced Repairs

An HVAC system that’s too big for your home will wear out faster because of constantly starting up and shutting down. The same thing will happen with a small-sized air conditioner that needs to work extra hard to cool the space. Extra wear and tear will push up the maintenance cost and may also shorten the lifespan of the unit, meaning you’ll need to replace it sooner rather than later.

  • Better air quality

When you install an oversized unit, the indoor air quality suffers. That’s because the HVAC system doesn’t run long enough to optimally dehumidify the indoor air. Also, if the AC unit runs only for shorter durations, it will fail to properly filter the air. As a result, the indoor air will contain contaminants (think pollutants such as dust mites, allergens, pet dander, viruses, mold, and more).

How Many Tons of AC Do I Need Per Square Foot?

Generally speaking, you require 1 ton of AC per 600 square feet. Keep in mind that many factors influence the air conditioning unit size. These include the heat and humidity levels outside, the number and style of windows, the orientation of your home, the number of heat sources inside the house, and whether your home is well insulated. So, if your home is not properly insulated, or if you live in an extremely hot city (such as Las Vegas), you may require 1 ton of AC per 400 square feet.

Estimating the Right Size Air Conditioning Unit for Your Home

Calculating the right air conditioner size is extremely important since every home is different, and a wrong-sized unit can cause all sorts of issues.  Thankfully, measuring the size of the HVAC unity for a room is easy. All you need to do is follow these three simple steps:

  • Determine the room’s length and width
  • Multiply these two numbers. For example, say your room’s length and width are 15 and 12 feet, respectively. So, it comes down to 180 square feet
  • Now, multiply the resulting number by 25 BTU for sufficient cooling. Continuing with the above example, you require the air conditioner to have a minimum cooling capacity of 4,500 BTU (180 x 25)

How Air Conditioner Sizes are Measured

While air conditioners are referred to as 1 ton, 2 tons, 3 tons, and so on, their capacity is calculated by factoring in the amount of heat (measured in BTU) they remove per hour. So, a one-ton air conditioner doesn’t actually weigh 1 ton; instead, this means that it can remove 12,000 BTU in an hour.

If you want to size your home’s air conditioning unit, use the following general guideline: one ton of AC is sufficient for a space of 600 square feet. 3 Main Factors Affecting the Size

  • Location: The greater the humidity and heat outside, the more time your air conditioning unit will take to cool the home. So, if you live in an extremely hot and humid city, you may need 1 ton of AC per 400 or even 350 square feet instead of 500 square feet.
  • Building Design: Homes facing toward the west or south usually take much longer to cool compared to those that face the east or north. That’s because these homes have greater direct sun exposure during the summer months. So, consider your building design when assessing your home’s air conditioning needs.
  • Ducting: The duct system distributes the conditioned air and as such can greatly impact your air conditioning unit’s performance. If the ductwork is improperly installed or the duct design is poor, your air conditioner will have to work extra to maintain your desired comfort level.

What are the other Variables that affect ac size?

  • Insulation: Insufficient insulation increases the cooling time of your air conditioner. This means you will likely need more than 1 ton of AC per 500 square feet. 
  • The number of windows: The number of windows — as well as their design — can have a major impact on the temperature inside of it. Having too many windows will increase the cooling process. Likewise, poorly designed or run down can severely affect your air conditioner’s ability to cool.
  • Ceiling height: A room with a high ceiling has a greater volume of air than a room with a standard height ceiling, and as such is much harder to cool in summer.  
  • Electrical appliances inside the home: The more electrical appliances inside the home, the higher the indoor temperature and the longer the cooling cycle will be.


Size does matter when it comes to air conditioning units. If the air conditioner’s size is appropriate for your home, it will run a proper full cycle, ensuring your space remains cool for longer.  An undersized unit is not enough and will have to run non-stop to maintain desired comfort levels. This can seriously increase your electricity bill in summer.  By contrast, an oversized air conditioner can be overkill because it will cool the space too quickly. As a result, it will not be able to properly dehumidify the indoor air.

Do yourself a favor and determine the size of the air conditioning unit your home needs. This will help you achieve optimum comfort and keep your energy costs down. Need help with this? Call 1.855.920.1857 to speak with a local HVAC professional.