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Wet Bulb Calculator

Enter dry-bulb air temperature and relative humidity to estimate wet-bulb temperature and dew point. Choose °C or °F. Results use RapidRatio’s decimal-first helpers—overview in why readable decimals matter.

Calculate wet-bulb temperature

Air temperature measured by a standard thermometer (not the wet bulb).
Percent from 0 to 100. Values above 0 are required for dew point.

Results

Wet-bulb temperature
Dew point
Enter dry-bulb temperature and humidity, then press Calculate.

What is wet-bulb temperature?

Wet-bulb temperature is the lowest temperature air can reach when water evaporates into it under constant pressure—a core idea in psychrometrics and moist-air thermodynamics. It combines the effects of dry heat and humidity and appears in weather analysis, HVAC design, and physics labs.

  • Dry-bulb — ordinary air temperature from a standard thermometer.
  • Relative humidity — how much moisture the air holds compared with saturation at that temperature, expressed as a percent.
  • Wet-bulb — always at or below dry-bulb for unsaturated air; equals dry-bulb when RH = 100%.
  • Dew point — temperature at which air becomes saturated and condensation begins.

Units, rounding, and limits

Choose °C or °F for input and output. Displayed temperatures use two decimal places. The wet-bulb estimate follows a common published approximation for typical indoor and outdoor ranges; extreme combinations may be less accurate. This model assumes standard atmospheric conditions and does not replace calibrated psychrometers or laboratory instruments.

FAQ

What is wet-bulb temperature?

Wet-bulb temperature is the lowest temperature air can reach by evaporating water into it at constant pressure. It reflects both heat and humidity and is used in psychrometrics, thermodynamics, weather, and HVAC.

What inputs does this calculator need?

Enter dry-bulb air temperature and relative humidity in percent. Choose Celsius or Fahrenheit for display. The tool returns approximate wet-bulb and dew-point temperatures in the same unit.

How accurate is the wet-bulb estimate?

This tool uses a published approximation suited to typical outdoor and indoor ranges. It is not a substitute for calibrated psychrometers or professional laboratory measurements.

Disclaimer. RapidRatio is informational only. It is not professional engineering, meteorological, or laboratory advice. Wet-bulb and dew-point outputs are estimates; verify measurements with calibrated instruments when precision matters.