Work out cooling load instantly with clear inputs, formula shown and shareable results.
A room cooling load is the sum of the heat pushed in through the envelope and the heat generated inside it. This estimate applies a 25 BTU/h per square foot envelope baseline, scales it for ceiling height and solar exposure, then adds roughly 500 BTU/h of sensible plus latent gain per occupant. Dividing by 12,000 converts the load into nominal tons of refrigeration.
Cooling load
Load = area x 25 x exposure factor x (height / 8) + occupants x 500; tons = load / 12000
Supply airflow
CFM = sensible BTU/h / (1.08 x supply air ΔT)
Preliminary estimate only. A Manual J or equivalent room-by-room load calculation by a qualified HVAC engineer is required for equipment selection and code compliance.
Load = area x 25 x exposure factor x (height / 8) + occupants x 500; tons = load / 12000. A room cooling load is the sum of the heat pushed in through the envelope and the heat generated inside it.
Load rules of thumb are calibrated to 8 ft ceilings. A taller room holds more air to cool and more wall area to gain heat through, so the load scales roughly with the height ratio.
This calculator takes 4 inputs: Floor area, Ceiling height, Occupants, Sun exposure. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.