Ton

By Anne Fonda

In the HVAC world, a ton is a unit of measurement we use to determine cooling capacity. HVAC tonnage refers to how much heat your AC unit can absorb rather than how much the unit weighs.

The larger in tons an air conditioning unit is, the larger the space it can cool. But bigger isn’t always better. Accurate AC sizing is crucial to your home's comfort and the ability of your cooling system to work efficiently.

If your AC unit is too big and powerful, it may cool your house quickly but not run long enough to lower the humidity, making you feel cold and clammy. Yuck. If the unit is too small, it won’t be able to cool every corner of your house like it should.

You need the Goldilocks central air conditioning unit, where the tons are just right.

The best way to correctly size an AC unit is to consult an HVAC professional. During a home visit, they will review several factors and perform a Manual J load calculation to determine which size you need. 

Factors they will consider include:

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

Notice that one ton is the equivalent of 12,000 BTUs per hour. BTU is the acronym for British Thermal Unit. One BTU measures the amount of heat required to raise or lower one pound of water by one degree Fahrenheit. 

The more BTUs, the more easily and efficiently an HVAC unit can heat or cool your home. But again, you want the units to be properly sized. If you can find the owner’s manuals for your current AC and furnace or heat pump, it will tell you the model number and potentially the serial number (if you wrote it in the manual.)

You can also look for the nameplate on the outdoor unit, usually on the side or back of the unit. In the U.S., the model number of your AC unit or heat pump may tell you the capacity. For instance, look for 24, 36, 48, or 60 in the model number. Those refer to the BTU output.

For example, for the AccuComfort™ Variable Speed Platinum Air Conditioner, one of the model numbers is 4A7V0X60. Since we know the BTU to tonnage ratio is 12,000 BTUs to 1 ton, without seeing the model specifications or the owner’s manual, you can tell that it is a 5-ton AC unit. (12,000 x 5 = 60,000).

When it comes time to replace the unit, chances are you will need the same size. But if your units were improperly sized, an HVAC professional can correct that and ensure you get a properly sized system.

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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 Kimberly Sexton, Senior Systems Engineer