Relative Humidity Calculator

Calculate humidity parameters such as relative humidity, dew point, frost point, vapor concentration, specific humidity, mixing ratio, and more parameters. - recommended humidity calculator for rotronic products.


PST Rotronic Relative Humidity Calculator

The PST Rotronic Relative Humidity Calculator is based on the Hyland and Wexler (1983) formula for measuring water vapor pressure over a range of temperatures.

It accurately represents the saturation vapor pressure of water over liquid and solid phases.

The Hyland and Wexler (1983) equation:
ln (Pvap) = A + B / (T + C)


Pvap is the water vapor pressure in Pascal (Pa).

T is the temperature in degrees celsius (°C).

A, B, and C are constants that vary depending on the water phase (liquid or solid).

The Humidity Calculator is built to focus on Relative Humidity measurement for engineers. Users can also choose between different units and parameter inputs such as dew point, wet-blub temperature, frost point, vapor concentration, and more. It can be used as a standalone tool or in combination with Rotronic humidity products.

How to use the Calculator

Using the PST Rotronic Relative Humidity Calculator is easy. 1) Choose the parameter you want to measure. 2) Enter the temperature and pressure. 3) Select the units in which you want to view your result.

Watch the quick video below demonstrating how to use the PST Rotronic Relative Humidity Calculator.

What is Relative Humidity?

Relative humidity is the measurement of how close the air (or other gas) is to being fully saturated with water vapor.

It is the ratio of water vapor pressure to saturation water vapor pressure expressed as a percentage.

%rh = (water vapor pressure/saturation water vapor pressure) * 100.0

Learn more about relative humidity and why it is measured for industries.


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