Proper System Sizing

Keep Your Cool with a Properly Sized AC System

The right size AC system for your home is good for your health, your comfort, and your wallet. When it comes to choosing an AC system for your home, size matters. An improperly sized system is an inefficient system. Whether it’s too small or too big for your space, it’ll mean higher energy costs.

An undersized AC unit will struggle to cool your home effectively. It’ll run overtime to meet your ideal thermostat setting. And you’ll never be as comfortable as you would with properly sized air conditioning.

Oversized AC units tend to cycle on and off frequently, leading to increased wear and tear on the system. The inconsistent airflow can lead to poor indoor air quality. As with an undersized system, you’ll feel the inefficiency in the form of higher energy bills and reduced comfort.

Understanding AC Sizing Measurements

The size of an air conditioning system is measured in tons. One ton of cooling capacity is equivalent to 12,000 BTUs (British Thermal Units) per hour.

When you see an air conditioning system listed as a “2-ton AC,” for example, it means that the system has a cooling capacity of 24,000 BTUs per hour. Most residential AC systems range in size from 1.5 to 5 tons.

The right size for your home will depend on a variety of factors, including your home’s square footage, insulation, and local climate. This is why it helps to have a professional size your AC system.

Signs that Your AC System is Not the Right Size

  • If it’s not the temperature you want. 

Is it never as cool as you like? Do some rooms feel cooler than others? These can be signs of inefficiencies in your AC system. One telltale sign of improper AC sizing is if your unit seems to be constantly running but not actually making your home more comfortable.

  • If you have higher energy bills than most.

An undersized AC system will need to run constantly, costing you more. An oversized system will cycle on and off, costing you more. And it can lead to additional problems, because an inefficiently large AC unit may have trouble removing humidity from your home. This can impact your air quality, increase your risk of mold growth, and impact your health in other ways.

Don’t Make This Common Mistake

Once you know the square footage of the space you’re trying to cool, it seems simple enough to choose the right AC size. Most manufacturers offer guidelines that help you choose the right AC size. But did you remember to add in the square footage of the hallway, or staircase, or other ancillary space that also needs to be cooled? This is a common mistake that leads to misjudgement of your cooling needs.

The Importance of Load Calculations

While your home’s square footage is an important factor, it’s not the only factor. A load calculation is necessary to AC sizing because it takes into account factors such as your home’s insulation, the local climate, and the number of occupants.

Load calculations are not a one-size-fits-all solution. Each home is unique, and the load calculation for your home may be different than your neighbor’s. For this reason, it’s important to work with a qualified HVAC professional to ensure that your AC system is properly sized for your home.

AC Sizing Chart: General Guidelines

To help you get started, we’ve created an AC sizing chart. This is just a starting point, and a load calculation should always be performed to ensure that your AC system is properly sized for your space.

Square Footage AC System Size
Up to 1,000 1.5 tons
1,000 – 1,500 2 tons
1,500 – 2,000 2.5 tons
2,000 – 2,500 3 tons
2,500 – 3,000 3.5 tons
3,000 – 3,500 4 tons
3,500 – 4,000 5 tons


Putting some thought into proper AC system sizing will keep you comfortable and protect you against unnecessarily high energy bills. The simplest method to properly size your AC is to work with a qualified HVAC pro like Wicked Cool. A proper AC size and expert installation will help you keep your cool, efficiently.

*The sizing above is informational only and not intended to replace proper sizing by a professional.

Was this article helpful?

Related Articles