Dew Point Calculator

Enter temperature and RH to estimate dew point, vapor pressure, absolute humidity, wet bulb and humidity ratio locally in your browser.

Temperature & humidity

Use measured air temperature and relative humidity. The result uses a Magnus-style vapor-pressure approximation.

Air temperature

Unit

Relative humidity (%)

Dew point is the temperature at which the same water-vapor pressure would reach saturation. It is not a forecast of whether dew will form on a particular surface.

Psychrometric Calculator Dew Point Relative Humidity Absolute Humidity Wet Bulb

Moisture state

—Dew point

—Actual vapor pressure

—Saturation vapor pressure

—Absolute humidity

Condensation & humidity evidence

Cross-check dew point, temperature-dew spread, vapor pressure and absolute humidity from the current inputs.

Humidity evidence

Metric	Value	Meaning

Condensation-threshold planner

Use air temperature + relative humidity above to calculate dew point, then compare it with a real surface temperature. The decision is whether a surface crosses the condensation threshold.

Surface temperatureSurface unit

—Dew point

—Surface margin

—Condensation risk

—Air–dew spread

Ready.

Check	Value	Meaning	Action

A surface at or below dew point can collect condensation even when ambient air is warmer.

One moist-air state, several related properties

Relative humidity, dew point, wet bulb, vapor pressure, absolute humidity and humidity ratio describe different parts of the same moisture state. WebToolArc keeps the selected inputs visible and shows related outputs together instead of treating the terms as interchangeable.

Accuracy boundary

These browser calculations use standard psychrometric approximations. Real measurements can differ because of sensor calibration, station pressure, ventilation, radiation, local gradients and the exact saturation-vapor-pressure formulation. Use calibrated instruments and applicable engineering or meteorological standards when decisions require certified measurements.