Dew Point Calculator Online & Excel File

As chemical engineers, we need to calculate the dew point in processes like gas drying, air compression, and HVAC control. For this, we have an online Dew Point Calculator in our chemical engineering tools list, which will help you just by entering the temperature and relative humidity.

Dew Point Calculator

Calculate dew point temperature from air temperature and relative humidity

Td = (b · α) / (a − α)   |   α = (a · T) / (b + T) + ln(RH / 100)

Air Temperature

%

Result Unit

Calculation Results

Magnus formula constants: a = 17.27, b = 237.7°C  |  Valid range: 0°C – 60°C air temperature, 1% – 100% RH.
Dew point cannot exceed air temperature — verify inputs if this occurs.
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FAQ (calculate dew point temperature)

1. How do you calculate dew point temperature?

Dew point can be calculated using air temperature and relative humidity. It’s the temperature where air becomes saturated and condensation begins.

2. How to find the relative humidity (RH)?

Relative humidity can be found using air temperature and dew point, with the Magnus equation for vapor pressure. It expresses how much moisture is in the air compared to the maximum it can hold at that temperature.

3. What inputs do I need for the Dew Point Calculator?

You just need to enter the air temperature and relative humidity. The calculator will instantly give you the dew point temperature.

4. Are there different equations to calculate dew point?

Yes. Methods include the Magnus–Tetens, WMO, and Goff–Gratch equations, plus simple approximations. Among them, Magnus–Tetens is the most common because it balances accuracy with ease of use.

Chemical engineer (B.Tech chemical & Post Diploma in Industrial Safety) with 7+ years of experience in operations/production & commissioning. Currently working on a greenfield polysilicon project. I publish hands-on process engineering guides at ChemicalTweak.com. Connect with me on LinkedIn.