Just Right: A Handy Air Conditioner Size Chart for Homeowners

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Just Right: A Handy Air Conditioner Size Chart for Homeowners

Not too big, not too small, just right. Goldilocks might have been talking about chairs, but the idea also applies to air conditioning systems.

No matter which type of air conditioning system you want, choosing the right-sized unit will cool your home more efficiently.

But, how do you decide what size AC you need?

Luckily, we’ve included a handy air conditioner size chart to help you calculate. Read on to learn how to find the right size air conditioner for your home.

Components of an Air Conditioner Size Chart

An air conditioner that is too small won’t be able to keep your home cool enough. It will also drive up your utility bill. The unit will need to run constantly to keep outside temperatures at bay.

If it’s too big, the air in your home will feel cool but humid. A unit that’s too large will cool off your home so quickly it won’t be able to take moisture out of the air. The air will feel muggy in your home.

Choosing the correct size for your home will keep you cool and prevent steep utility bills. The most important components of a sizing chart are BTUs and square footage.


BTUs, or British Thermal Units, measure the amount of heat an air conditioner can remove from the air in an hour. In other words, BTUs measure the cooling power of an air conditioner.

If you’re considering central air, tonnage is another measurement to be aware of. It is a term used to measure central air units and is related to BTUs. For example, a one-ton air conditioner has 12,000 BTUs and a two-ton has 24,000 BTU capacity.

Square Footage

To calculate the square footage of a room, multiply the width by the length of the room. This figure is the square footage. For example, if a bedroom is 10 feet wide and 12 feet long, the square footage of that room would be 120 square feet.

If you are planning to cool several rooms in your home, find the square footage of each room and add those figures together.

More Factors to Consider

While square footage is a good place to start measuring, there are many other factors that will affect the amount of BTUs you need.

High ceilings and rooms with lots of windows will increase the amount of BTUs you’ll need. That’s because sunny rooms are naturally warmer, so you’ll need more cooling power to keep those rooms comfortable.

On the other hand, if your house is heavily shaded by trees or is built on a slab (rather than a basement foundation), you won’t need as many BTUs. Your home naturally stays cooler so you won’t need as much air conditioning power.

Get a Technician’s Opinion

When it comes to an air conditioning system, there are a lot of variables at play. Using an air conditioner size chart is a great way to get a ballpark idea for the size you need.

Still not sure what size air conditioner you need? A trained technician can calculate the best air conditioner size for your home. Contact us today to make an appointment.

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