Free Engineering Tool
Psychrometric Chart Calculator
Interactive psychrometric chart with ASHRAE-grade accuracy. Calculate moist air properties, simulate HVAC processes, and export results — all in your browser.
Capabilities
Complete Air Properties
Dry bulb, wet bulb, dew point, humidity ratio, enthalpy, specific volume, density, and vapor pressure — all calculated in real time.
Interactive Chart
Canvas-based psychrometric chart with click-to-set, drag state point, zoom, and pan. Saturation curve, RH lines, wet bulb lines rendered at 60fps.
HVAC Process Simulation
Simulate sensible cooling, cooling with dehumidification, sensible heating, humidification, and air mixing directly on the chart.
SI and IP Units
Switch between SI (°C, kJ/kg, g/kg) and IP (°F, Btu/lb, grains/lb) with one click. All properties convert instantly.
Export PNG & CSV
Export the chart as a high-resolution PNG or download all calculated properties as CSV for reports and documentation.
ASHRAE-Grade Accuracy
Hyland-Wexler saturation pressure formulation from ASHRAE Handbook — Fundamentals 2017. Newton-Raphson iteration for wet bulb and dew point.
5 HVAC processes
Add up to 5 simultaneous processes and visualize them directly on the psychrometric chart with colored paths.
Sensible Cooling
Constant W, lower T
Cooling + Dehum.
Below dew point
Sensible Heating
Constant W, higher T
Humidification
Increase RH
Air Mixing
Blend two streams
10 air properties calculated instantly
Enter any two independent properties and all others are computed using ASHRAE Hyland-Wexler correlations.
Technical references
- [1]Hyland, R.W. & Wexler, A. (1983). Formulations for the Thermodynamic Properties of the Saturated Phases of H₂O. ASHRAE Transactions, 89(2A), 500-519.
- [2]ASHRAE Handbook — Fundamentals (2017), Chapter 1: Psychrometrics.
- [3]Buck, A.L. (1981). New Equations for Computing Vapor Pressure and Enhancement Factor. Journal of Applied Meteorology, 20(12), 1527-1532.
Start calculating now
Free to use with your ExCoil account. No installation required.