Dew Point Calculator

About Dew Point Calculator

Dew Point Calculator uses the Magnus formula to compute the dew point temperature from air temperature and relative humidity. The dew point is the temperature at which air becomes saturated and water vapour condenses into dew. Results are shown in both °C and °F, along with a comfort label: Dry (below 10°C), Comfortable (10-15°C), Humid (16-20°C), or Very Humid (above 20°C). The dew point is a more reliable indicator of perceived humidity than relative humidity alone. A relative humidity of 80% on a cold day feels less oppressive than 60% on a hot day because the actual amount of moisture in the air is lower. When the dew point exceeds 20°C, most people find the air uncomfortably muggy regardless of the air temperature.

How to use Dew Point Calculator

  1. Enter air temperature in °C or °F
  2. Enter relative humidity as a percentage
  3. See dew point in °C and °F with a comfort label

Frequently Asked Questions

What is the dew point?
The dew point is the temperature at which air at a given humidity level becomes saturated with water vapour and dew starts to form. A higher dew point means more moisture in the air and a more humid feeling.
What formula is used?
The calculator uses the Magnus formula: y = (a x T)/(b+T) + ln(RH/100), then Td = b x y/(a-y), where a = 17.27, b = 237.7, T is air temperature in °C, and RH is relative humidity in percent.
What comfort levels are shown?
Dry: dew point below 10°C. Comfortable: 10-15°C. Humid: 16-20°C. Very Humid: above 20°C. These correspond to how muggy the air feels to most people.
What dew point feels uncomfortable?
A dew point above 16°C starts to feel humid to most people. Above 20°C, conditions feel oppressive and muggy. Tropical climates regularly reach dew points of 25°C or higher, which most people from temperate climates find very uncomfortable.
What is the difference between dew point and relative humidity?
Relative humidity is a percentage that expresses how close the air is to saturation at the current temperature. It changes with temperature even when the actual moisture content stays the same. Dew point is an absolute measure of moisture content and does not change with temperature, which makes it a more reliable comfort indicator.
Is Dew Point Calculator free and private?
Yes. Dew Point Calculator is completely free with no account required. All calculations run in your browser and nothing is uploaded or stored.
Does Dew Point Calculator work on mobile?
Yes. Dew Point Calculator is fully responsive and works in all modern browsers on desktop, mobile, and tablet.

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