This dew point calculator determines either of the three dew point temperature, air temperature and relative humidity in percentage from the rest of two. Read more on this subject and check the equations used below the form.

Please fill in ONLY 2 of the 3 fields below, in order to find the third variable!

Air temperature:
Relative humidity:
Dew point temperature:

How does this dew point calculator work?

This is a tool designed to estimate the dew point temperature based on air temperature and relative humidity in percentage but can also find either air temperature or the relative humidity in case the dew point temperature is given.

The Dew Point calculator can perform any of the following dew point calculations, one at a time:

  • Retrieve the dew point temperature in Celsius (°C), Fahrenheit (°F) and Kelvin (°K) when air and relative humidity are known.

DP=((RH/100)^(1/8)*(112+0.9*AT) )+(0.1*AT)-112

  • Determine air temperature in the three units in case dew point and relative humidity are filled in the form.

AT= (DP-(112*(RH/100)^(1/8))+112)/((0.9*(RH/100)^(1/8))+ 0.1)

  • Estimate percentage of relative humidity



DP = dew point temperature in Celsius (°C).

AT = air temperature in Celsius (°C).

RH = relative humidity (%).

Formula’s source: Martin Wanielista, Robert Kersten & Ron Eaglin, 1997 - Hydrology Water Quantity and Quality Control. John Wiley & Sons - Second edition.

When the calculator needs to display the temperature in Celsius (°C), Fahrenheit (°F) and Kelvin (°K) the following conversions are being used:

1 °C = 33.8 °F

1 °C = 274.15 °K

What is dew point?

This is considered the temperature at which the water vapor in a sample of air at constant pressure condenses into liquid water at the same rate at which the water vapor evaporates. This explains the forming of dew or fog when air temperature cools to the dew point and the relative humidity is 100%.

This also explains how precipitations like rain form, when there is further cooling of the air and more vapors condense and then the dew point falls following the air temperature.

Basically, dew point is an indicator of how much water vapor is in the air at a certain moment and the higher it is, the more humid we perceive the air to be. It is an absolute value measured by dew point meters over a wide range of temperatures and they are often used in calibration of humidity sensors in industry.

26 Mar, 2015