What is the AC Tonnage Calculator?
The AC Tonnage Calculator helps homeowners and HVAC professionals determine the precise cooling capacity needed for a specific room or entire house. By calculating the correct tonnage, you ensure your air conditioning unit cools efficiently without short-cycling or wasting energy. (Inputs automatically support metric or imperial conversions).
How to Calculate AC Tonnage (Formulas)
Air conditioning capacity is measured in British Thermal Units (BTUs). One "ton" of cooling capacity is equal to 12,000 BTUs per hour.
- Base BTU Formula: Square Footage of the room * 20 BTUs.
- Tonnage Formula: Total BTUs / 12,000.
Note: If a room has vaulted ceilings, excessive windows, or is a kitchen, you must add a 10% to 20% multiplier to the base BTU calculation.
Frequently Asked Questions
How many tons of AC do I need for a 1,500 sq ft house?
Using the standard formula (1,500 sq ft * 20 BTUs), you need 30,000 BTUs. Dividing this by 12,000 BTUs per ton yields a requirement of 2.5 tons. However, this can vary based on your climate zone and home insulation.
What happens if my AC unit is too big (oversized)?
An oversized AC unit will cool the house too quickly and shut off (a process called short-cycling). Because it doesn't run long enough, it fails to remove humidity from the air, leaving your home feeling cold and clammy.
What is an AC Ton?
An AC "ton" has nothing to do with the physical weight of the unit. It refers to the amount of heat required to melt one ton (2,000 lbs) of ice over a 24-hour period, which equates to 12,000 BTUs per hour.