HVAC Calculator: BTU & AC Load

Two new calculators — and a faster way to reach all of them. DUCT SIZE CALCULATOR Size round and rectangular duct by the equal-friction method. Enter airflow in CFM or m³/h, choose a friction rate, and get the exact diameter, the nearest standard duct size, and an air velocity check that warns you before a run turns noisy. Rectangular ducts show width × height plus the equivalent round diameter. HEAT LOAD CALCULATOR Estimate the cooling load room by room for a whole property. Add each room with its dimensions, sun exposure, occupants and kitchen, then read the total in BTU/h, tons and kW with a per-room breakdown — a quick first pass before a full Manual J. FAN TO DUCT IN ONE TAP Work out exhaust airflow, then send that CFM straight into the duct sizer without typing it again. NEW CALCULATORS SCREEN Air conditioning, exhaust fan, duct size and heat load now sit together on one screen instead of separate tabs. ALSO IN THIS UPDATE • Saved projects now hold duct and heat load calculations too • Both new calculators translated into all 20 supported languages Every calculation still runs offline, in metric or imperial.