Psychrometric Chart

A psychrometric chart is a graphical representation of the thermodynamic properties of moist air, providing engineers and HVAC professionals with a powerful tool for analyzing air-conditioning processes and thermal comfort conditions. The chart plots key variables including dry-bulb temperature (x-axis), humidity ratio (y-axis), relative humidity (curved lines), enthalpy (diagonal lines), and wet-bulb temperature (inclined lines) on a single diagram. The saturation curve (100% RH line) forms the upper boundary, showing air’s maximum moisture capacity at each temperature. By tracing state points and process lines on the chart, users can visualize:

  • Cooling/dehumidification (movement left and downward from a point)

  • Heating/humidification (movement right and upward)

  • Evaporative cooling (horizontal movement along constant wet-bulb lines)

  • Sensible heat ratio (slopes of conditioning processes)

The chart’s intersecting property lines reveal how changing one parameter (e.g., temperature) affects others while conserving energy (enthalpy) or moisture (humidity ratio). This enables precise calculations for equipment sizing, energy efficiency optimization, and comfort zone analysis in HVAC system design

Advanced Psychrometric Chart

Interactive Psychrometric Chart

Mouse over the chart to see properties at any point
25.0°C
50%
101.325 kPa

Air Properties at Current State Point:

Wet Bulb Temp:
18.4°C
Dew Point Temp:
14.0°C
Humidity Ratio:
0.0098 kg/kg
Enthalpy:
50.5 kJ/kg
Specific Volume:
0.855 m³/kg
Vapor Pressure:
1.58 kPa