AC Tonnage Calculator

AC tonnage refers to the cooling capacity of an air conditioner. One ton equals 12,000 BTU per hour. Proper tonnage is crucial - too small won't cool effectively, while oversized units cycle on/off frequently, wasting energy and reducing humidity control.

Calculate your room's square footage, then multiply by 20-25 BTU per square foot as a baseline. Add extra BTU for occupants (600 BTU each), windows (1,000 BTU each), and other heat sources. Divide the total BTU by 12,000 to get tonnage.

BTU (British Thermal Unit) measures the amount of heat energy needed to raise one pound of water by one degree Fahrenheit. AC tonnage is simply BTU divided by 12,000. For example, a 24,000 BTU unit equals 2 tons.

A 1.5-ton AC unit (18,000 BTU) typically covers 600-900 square feet, depending on ceiling height, insulation, number of windows, and climate zone. Well-insulated homes with standard 8-9 foot ceilings are at the higher end of this range.

Manual J is the industry-standard method for calculating heating and cooling loads in residential buildings. It considers detailed factors like climate zone, building materials, orientation, and internal heat gains to provide the most accurate sizing recommendations.

Yes, different rooms have varying cooling needs. Kitchens need extra capacity due to appliances generating heat. Bedrooms may need less since they're typically used at night when temperatures are cooler. Living rooms fall in the middle range.

Higher ceilings increase the volume of air to be cooled. For ceilings over 9 feet, add about 10% more cooling capacity for each additional foot. This accounts for the increased air volume and potential heat stratification.

An oversized AC will cool the space too quickly without adequate dehumidification, leading to a cold, clammy environment. It will also cycle on and off frequently, reducing efficiency, increasing wear, and raising energy costs.