HVAC calculators

Each calculator runs in your browser and shows the math and the sources it uses. They are for planning and checking quotes. They do not replace a Manual J load calculation by a contractor.

• Room air conditioner BTU calculator

  Find the BTU size for a window or portable air conditioner from room size, sun, people and kitchen use, using the ENERGY STAR sizing chart.

• Central AC tonnage calculator

  Turn square footage into a ballpark central air conditioner size in tons and BTU/h, using both rules of thumb in the DOE heating and cooling guide.

• SEER2 savings calculator

  Compare yearly cooling electricity use and cost for two SEER2 ratings, and see the payback on a higher-efficiency air conditioner or heat pump.