What Size AC Unit Should I Get for My Home or Office?

AC unit outside in Hudson

Having the right sized air conditioner is a key component in cooling your space effectively. A unit that is too small has to run constantly, playing catch up all day trying to fill a space that it isn’t designed for. A unit that is too big will turn on, cool the space quickly and then shut off, which sounds good but the heat will come back in and the unit will click back on and then back off. This on, off, on, off uses a lot of energy and more energy equals more money. At Chaves Heating & Air Conditioning, we are in the business of keeping you cool and saving you money.

Air conditioners are measured by tons, but this isn’t the weight of your appliance in tons. The tonnage of an AC unit is based on how much the unit can cool. A 1 ton air conditioner = 12,000 BTUs.

A BTU or British Thermal Unit is the unit of energy that equals 1055 jules. One BTU is the amount of energy needed to cool 1 pound of water by 1 degree Fahrenheit. A one ton AC unit can cool 12,000 pounds of water by 1 degree, each hour.

Home units can be anything from a 1-5 ton unit and they increase by .5’s as they go up. Size matters, but bigger is not necessarily better, having an accurately sized unit is the way to go.

The old school equation to finding out the right size unit for you is as follows:

The square footage of your space multiplied by 25, divided by 12,000, then subtract .5.

Climate zones also make a difference in determining the correct unit for you, so you can follow the equation or contact us for help! We are happy to assist you in finding the right appliance for your home.

Call us today at 978-562-5309 or request service online.

Need Air Conditioning Service?

Call us at 877-7-CHAVES or schedule your AC service online.


Chaves Heating & Air Conditioning provides heating, cooling, indoor air quality, commercial, and HVAC maintenance services to residents in Acton, Bolton, Clinton, Concord, Framingham, Lancaster, Leominster, Shrewsbury, Upton, Worcester, and other surrounding Massachusetts communities. Visit our service area page to learn more about how we can service you and to view the other communities in our core service area. Contact us today at 877-7-CHAVES or schedule service online.

Need HVAC Service?

Contact the experts at Chaves HVAC.

Call us at 978-562-5309!

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