HVAC Calculator - FieldCalc

R-410A is out, R-454B is in. Get PT charts, superheat & subcooling, duct sizing, psychrometrics & load estimates — all offline, one app. Built for HVAC technicians.

FieldCalc HVAC is the all-in-one field calculator for HVAC technicians. From R-454B PT lookups to duct sizing and load estimates — everything you need, working offline, right in your pocket.

► R-454B READY The industry is switching from R-410A to R-454B. Get instant pressure-temperature data for R-454B, R-32, R-410A, plus 10 more refrigerants (R-134a, R-22, R-404A, R-407C, R-448A, R-449A, R-507A, R-1234yf, R-452A, R-513A). Drag the temperature slider and see bubble/dew pressures in real time. Includes GWP and ODP data for every refrigerant.

► SUPERHEAT & SUBCOOLING Verify refrigerant charge on the spot. Enter suction or liquid pressure, line temperature, and your target — get instant superheat or subcooling with a clear status indicator (green/amber/red) and diagnostic guidance.

► DUCT SIZING Size round and rectangular ducts using the equal-friction method (ASHRAE Fundamentals / Manual D methodology). Enter airflow and friction rate — get diameter, velocity, and a velocity-range check for main vs. branch ducts.

► LOAD ESTIMATE Quick cooling load estimates using Manual J methodology (simplified). Enter floor area, climate zone, windows, occupants, and appliances — get total BTU/h, tons, and a recommended unit size with a breakdown bar.

► PSYCHROMETRICS Calculate dew point, wet bulb, enthalpy, humidity ratio, and vapor pressure from dry-bulb temperature and relative humidity. Includes a mini psychrometric chart with the state point plotted.

► UNIT CONVERTER Convert between °F/°C/K, PSIG/kPa/bar/MPa, CFM/m³·h/L/s, and BTU/h/kW/tons/hp — instantly, with conversion formulas shown.

WHY FIELD CALC HVAC? • Works 100% offline — no internet needed on the roof or in the mechanical room • Every calculation shows its work — formulas, substitution, and standard references • Save calculations to history, pin your favorites, add notes for each job • Export professional PDF reports • Clean, modern interface designed for one-handed field use • Light & dark themes

DATA SOURCES Refrigerant PT data is factual physical property data sourced from manufacturer publications (Honeywell, Chemours, Arkema), Hudson Technologies PT charts, and NIST Refprop. Calculations reference ASHRAE Fundamentals and ACCA Manual J/D methodology. FieldCalc HVAC is not affiliated with or endorsed by ASHRAE or ACCA.

FREE vs PRO Free: Unit Converter, PT Charts (3 refrigerants: R-454B, R-32, R-410A) Pro ($9.99 one-time): All 5 calculators, full refrigerant library (13), history, PDF export, and all future updates.

No subscription. No ads. No data collection. Buy once, own forever.