What Size Central AC Should You Get?

What Size Central AC Should You Get?

What Size Central A/C Should You Get?

What size central air conditioner do you need? There are many factors in your home that determine the size of your central air conditioner.

When you compare different central air conditioners, you will see terms like “tonnage,” “BTU,” “energy efficiency,” or “load calculation”. It can be confusing.

To help you find the ideal size central air conditioner for your home, let’s look at each of these terms in simple, straightforward explanations.


BTU means British Thermal Unit and is the measure of how much heat is given off when fuel is consumed. In practical terms, it is the amount of energy needed to heat the air or to remove heat from the air.

Energy Efficiency

Energy efficiency means simply using the least amount of energy possible to perform a task. The more efficient an A/C unit is, the less energy it will consume to produce the same cooling effect. Air conditioner energy efficiency is measured in SEER (Seasonal Energy Efficiency Ratio). The higher the SEER rating, the more energy efficient a system is.

The minimum SEER rating for air conditioners is 14, but many units have a rating between 13 up to 25. The unit’s rating could make a significant difference to your energy cost. For instance, a 16 SEER unit uses roughly 13% less energy than a 14 SEER unit for the same amount of cooling.


Central air conditioners come in different sizes that are measured by tonnage. Tonnage isn’t about how big, broad, or bulky you’re A/C unit is; it’s about how much cooling capacity you can enjoy from you’re A/C. Each ton is equal to the amount of energy required to melt one ton of ice over a 24-hour period.

The tonnage required is largely determined by the size of your home.


Let’s look at why buying the right size is always the best decision.

Generally, central air conditioners slowly cool the temperature in your home by running in cycles. The reason they keep your home comfortable is they regulate the temperature and don’t cool the air down too rapidly, which would increase your energy bills.

When you buy a central A/C that is oversized, it will turn on and off without running the full cycle. Your home will cool very quickly but will result in high energy bills. Additionally, because an oversize unit will turn off quickly, it doesn’t get the chance to effectively dehumidify the air.

On the other hand, when you buy a unit that’s too small, it will run without stopping as it strives to achieve the impossible task of cooling your home optimally and will increase your energy bills significantly.

Buying the right sized central A/C will help you reap the benefits of having your unit run through a full cycle before shutting off for a while. It provides a comfortable home at the lowest energy consumption possible.

Load/Tonnage Calculation

Based on some of the information on the internet, you might think that it’s a simple matter. There is a “standard” formula of square footage times 30, divided by 12,000 minus 1. For example, a 2,000 sq.ft. home would be

(2000 x 30/12,000) – 1 = 5 tons

But this is not a “one size fits all” method of properly determining what size unit is required. There are many other factors that must be taken into account.

Other Factors

When calculating the size of A/C system required, there are many factors besides square footage that must be taken into consideration:

  • Ceiling height
  • The existing ductwork
  • The number and size of windows and skylights
  • The quality and amount of insulation
  • Climate and humidity levels
  • Heat transfer through the walls
  • The number of heat-generating appliances
  • The number and size of trees around your home that could be providing protection from the sun.
  • The type and color of your roof
  • Whether your house has a basement or a slab

Get Professional Help

Selecting the right size central air conditioning unit for your home depends on many factors. It is very wise to consult an HVAC professional to help you select the right central conditioning unit for your home.

At Forney Air, we recognize the need for an effective heating and air-conditioner system that will keep your home comfortable for many years. We will conduct a complete analysis of your needs to help you determine the size and efficiency of the central A/C system you should get.

All our new installations are turnkey. We handle the supply and installation of the new system and disposal of your old unit.

Call the experts at Forney Air today at (214) 924-9745 or contact us online for your free estimate on new systems installations.


New Central Air Conditioner

Unbeatable Financing Offer