Dewpoint Calculator for Moisture Measurement

For Trace Moisture Measurements in Gases & Air

The dewpoint calculator will convert between various units of measurement. To use, simply enter a number in either one of the two dewpoint values, selecting appropriate units, or one of the four absolute values before pressing the calculate button. ‘Line Pressure’ and ‘Gas Type’ are only required as inputs if the ‘dewpoint at line pressure’ or ‘ppm(w)’ are to be calculated. You can choose from seven common gases or enter known moleculer weight and line pressure units can be changed to bara, barg, psia, psig, KPa and MPa.

Please press the “Reset” button after each calculation to clear the fields.

Dewpoint Values

Dewpoint at Atmospheric Pressure:

Optional Inputs

Line pressure:

Gas Type:

Input a gas of known molecular weight or select blank from the dropdown menu to input a custom value

Absolute Values

Parts per million by volume:


Parts per million by weight:


Absolute humidity:



Pressure Dewpoint

Dewpoint at Line Pressure:


Whilst every effort has been made by Alpha Moisture Systems, to ensure that the calculations derived by the moisture calculator are correct, it assumes no responsibility for any errors. In no event shall Alpha Moisture Systems be liable for any damages whatsoever arising from, or relating to, information contained in this site.

SADPmini2 User App

The Alpha Moisture Systems Dew point Calculator is also available via the SADPmini2 User App which is available for Android and iOS devices.