HVAC Calculator - FieldCalc

The professional HVAC calculator for technicians and contractors. Superheat, subcooling, R-454B PT charts, duct sizing, load estimates, and psychrometrics — six field-ready tools, all offline, in one app.

Whether you're charging a system with R-454B, checking superheat with your manifold gauge, sizing a duct run, or estimating cooling load for a new install, FieldCalc HVAC gives you instant, transparent answers — no internet required.

► R-454B & A2L READY
The industry is switching from R-410A to R-454B and other low-GWP A2L refrigerants. 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 (CFM) and friction rate — get diameter, velocity (FPM), 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.