What Size Air Conditioner Do I Need for My Home?


If you’re shopping for a new air conditioner, chances are that you’ve already seen how many choices there are. To be honest, it can be a little overwhelming, especially if you’re not familiar with these types of units. At Guaranteed Comfort Heating & Cooling, we’re available to assist you with your AC installation if you live in Windsor or the surrounding areas. In the meantime, here’s an overview of how air conditioners are sized.

The Importance of BTUs

When we discuss the size of air conditioners, we’re really referring to how much heat they can remove from an area, and that’s measured in BTUs. BTUs are British thermal units. BTUs have been used for some time to quantity energy in the form of heat. One BTU is the amount of energy it takes to increase the temperature of 1 pound of water by 1 degree.

We want to be sure to point out that BTUs are actually used to describe how much heat can be added to an area. This is why appliances like stoves and grills can all be described with BTUs. When it comes to AC units, BTUs tell you how much heat is removed from the air.

A general rule is that 20 BTUs are necessary to effectively cool 1 square foot of space. This means that 100 square feet of space could be cooled by a unit with 2,000 BTUs, and that a 500-square-foot room could be cooled by an AC with 10,000 BTUs.

BTUs and Tons

BTUs are great when referring to air conditioners designed for a single room. They’re also ideal for referring to ACs that are built to cool entire homes, but there’s yet another term that you often see in the industry. Larger AC units are described in tons, like 1-ton units, 2-ton units, and so on. You might be able to find some 5-ton units, but most residential homes don’t use anything bigger than that.

Before electricity and all of our advanced systems, people used huge blocks of ice as cooling agents. The ice would absorb heat from the area to cool things down, and it would obviously melt over time. Industry experts figured out that it took about 288,000 BTUs to melt a ton of ice in a day. That translates to approximately 12,000 BTUs per hour. From this, we get to the idea that a 1-ton air conditioner has about 12,000 BTUs. It’s a linear relationship, so a 3-ton unit has around 36,000 BTUs.

For a smaller home with about 1,000 square feet, a 1.5-ton AC unit should work. A home with about 1,500 square feet would probably need a 2.5-ton unit, a 1,750-square-foot home could use a three-ton unit, and a home with more than 2,000 square feet would need at least a 3.5-ton unit.

There are several things that affect which size air conditioner is right for your particular home. They include:

  • The climate in your region
  • How much shade your yard has
  • How many windows you have and what direction they face
  • What type of insulation there is
  • If the home has an open or closed layout

A professional can come in and assess your home, taking into account all of the factors mentioned above as well as a few other things. Since an air conditioner does require a significant investment, it can be a smart idea to consult with a trained expert to ensure that you’re putting your money into something that will do its job properly.

Look to Us for Assistance

You can let us handle your AC installation for you. From helping you select a model to hooking everything up properly, we’ll take care of everything in a professional manner. We’ve been in business for over 25 years, and we work with all makes and models. Our company has earned an A+ rating with the Better Business Bureau, and we’re fully licensed and insured.

At Guaranteed Comfort Heating & Cooling, we’re always happy to answer questions from folks in the Windsor community. We provide free estimates on new and replacement systems, and many units qualify for a 10-year warranty on parts and labor. In addition, with many units, you could get 10 years of annual maintenance for no extra charge. Our company is the one to turn to for service on water heaters, air purification systems, and repairs, installations, and maintenance on heaters and air conditioners. Give us a call to set up an appointment.

Chris Egan


Chris Egan, owner of Guaranteed Comfort Heating & Cooling, brings over 35 years of HVAC experience. Dedicated to customer satisfaction, he delivers top-notch heating and cooling solutions.