Capacity

By Anne Fonda

HVAC capacity is the output or production capability of a piece of heating or cooling equipment. Central air conditioning capacity and heating capacity are measured in tons or BTUs.

Air conditioner capacity is measured in tons, sometimes referred to as tonnage. It does not refer to the weight of the AC unit. Determining the capacity in tons that you need to cool your home involves precise AC sizing. 

This is best done by an HVAC professional who will take into account multiple factors that they will enter to perform a Manual J load calculation. Factors they consider include:

You can also estimate the sizing using the square footage of your home, as indicated by the AC sizing chart below. 

Notice that one ton translates to 12,000 BTUs. More on that below.

BTU stands for British Thermal Units. One BTU refers to the amount of heat that’s needed to raise or lower one pound of water by one degree Fahrenheit. The heating capacity of a furnace or heat pump is usually measured in BTUs, but BTUs can also be used to measure the capacity of central air conditioners and ductless HVAC systems. 

To calculate heating capacity, you will also need to consider the square footage of your home, the climate, and your heating needs. Again, an HVAC professional can help with this. The colder the climate zone, the more BTUs, or heating capacity you will need.

You can get an idea of how many BTUs your furnace or heat pump needs by using this online BTU calculator. Keep in mind that a higher-efficiency furnace or heat pump will have a higher actual output.

Wondering what size AC unit you need or how many BTUs your furnace should have? Contact your local American Standard dealer for precise system sizing.

Anne Fonda, Content Writer

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need. 

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Mark Woodruff, Senior Product Manager, Ducted Outdoor