Free · no sign-up · nothing to install
The same math as the app, running right here. Every result comes with the formula, the source it came from, and a plain-English verdict on whether the number is in range. Built for the tech on the job, not for a homework set.
Gauge pressure and line temperature in, superheat or subcooling out, with a verdict against the target. R-410A, R-454B, R-32, R-22. Target superheat for fixed-orifice systems too.
Open the calculator →Free · runs in your browserRound or rectangular duct size for any airflow and friction rate, with the velocity check that tells you if it will be noisy.
Open the calculator →Free · runs in your browserAirflow from tonnage, from furnace temperature rise, or from room air changes — the three ways techs actually need CFM.
Open the calculator →They do not save anything, they do not work without a signal, and they do not read a data plate. HVAC Pro Calculator on iOS does those: saved jobs with iCloud, offline everything, PlateScan to decode tonnage and refrigerant from the model number, and PDF export for the customer. The field guidesexplain the methods behind each calculator.
Duct sizing is listed as a Pro feature. See the App Store and in-app offer for current access, plans and eligibility.
