Psychrometric Calculator

Calculate Dew Point, Wet Bulb, Enthalpy, and More

Enter air temperature, relative humidity, and pressure to compute key psychrometric properties for HVAC, meteorology, and science.

Examples

See how psychrometric calculations work in real scenarios.

Standard Room Air

Standard Room Air

25°C, 60% RH, sea level pressure.

Dry Bulb Temp (°C): 25 °C

Relative Humidity (%): 60 %

Pressure (hPa): 1013.25 hPa

Humid Summer Day

Humid Summer Day

30°C, 80% RH, 1005 hPa.

Dry Bulb Temp (°C): 30 °C

Relative Humidity (%): 80 %

Pressure (hPa): 1005 hPa

Dry Winter Air

Dry Winter Air

5°C, 30% RH, 1020 hPa.

Dry Bulb Temp (°C): 5 °C

Relative Humidity (%): 30 %

Pressure (hPa): 1020 hPa

High Altitude

High Altitude

15°C, 50% RH, 850 hPa.

Dry Bulb Temp (°C): 15 °C

Relative Humidity (%): 50 %

Pressure (hPa): 850 hPa

Other Titles
Understanding the Psychrometric Calculator: A Comprehensive Guide
Master air property calculations for science, engineering, and daily life.

What is the Psychrometric Calculator?

  • Definition and Purpose
  • Key Psychrometric Properties
  • Why Accurate Air Analysis Matters
The Psychrometric Calculator is a scientific tool designed to compute the thermodynamic properties of moist air. It uses temperature, humidity, and pressure to determine values like dew point, wet bulb temperature, enthalpy, and more.
Key Properties Calculated
  • Dew Point: The temperature at which air becomes saturated and water vapor condenses.
  • Wet Bulb Temperature: The lowest temperature air can reach by evaporative cooling.
  • Enthalpy: The total heat content of air.
  • Specific Humidity: The mass of water vapor per kilogram of dry air.

Real-World Examples

  • A meteorologist uses the calculator to predict fog formation.
  • An HVAC engineer checks enthalpy for energy-efficient cooling.

Step-by-Step Guide to Using the Psychrometric Calculator

  • Input Requirements
  • Calculation Process
  • Interpreting Results
To use the calculator, enter the dry bulb temperature, relative humidity, and atmospheric pressure. The tool then applies psychrometric equations to compute all major air properties instantly.
How to Read the Output
Results include dew point, wet bulb temperature, enthalpy, specific humidity, vapor pressure, and humidity ratio. Each value helps you understand air moisture and energy content.

Step-by-Step Examples

  • Entering 25°C, 60% RH, 1013.25 hPa gives a dew point of 16.7°C.
  • A high-altitude input (15°C, 50% RH, 850 hPa) shows lower vapor pressure.

Real-World Applications of the Psychrometric Calculator

  • HVAC and Building Design
  • Weather Forecasting
  • Industrial Processes
Psychrometric calculations are vital in HVAC system design, weather prediction, and industrial drying or humidification. Accurate air property data ensures comfort, safety, and efficiency.
Where is it Used?
  • HVAC: Sizing air conditioners and dehumidifiers.
  • Meteorology: Predicting dew, fog, and precipitation.
  • Industry: Controlling drying, fermentation, and storage environments.

Application Examples

  • An engineer sizes a dehumidifier for a swimming pool.
  • A food technologist monitors drying air in a factory.

Common Misconceptions and Correct Methods

  • Misreading Humidity
  • Ignoring Pressure Effects
  • Using Outdated Charts
Many users confuse relative and absolute humidity, or neglect the impact of pressure on air properties. Modern calculators provide more accurate results than old psychrometric charts.
Best Practices
  • Always use current atmospheric pressure for altitude.
  • Double-check input units.
  • Prefer digital calculators for precision.

Misconception Examples

  • A user enters sea level pressure for a mountain site and gets wrong results.
  • Switching from a paper chart to this calculator improves accuracy.

Mathematical Derivation and Examples

  • Key Equations
  • Worked Example
  • Advanced Tips
The calculator uses established formulas for each property. For example, dew point is derived from Magnus formula, enthalpy from air and vapor content, and wet bulb from psychrometric relationships.
Sample Calculation

Given 25°C, 60% RH, 1013.25 hPa:

  • Dew Point = 16.7°C (Magnus formula)
  • Wet Bulb = 19.1°C
  • Enthalpy = 56.8 kJ/kg
  • Specific Humidity = 13.8 g/kg

Mathematical Examples

  • Try the example values in the calculator to verify results.
  • Use advanced mode for custom pressure or unit conversions.