Dew Point Calculator
The dew point is the temperature to which air must cool, at constant pressure, for water vapor to start condensing into dew, fog or clouds. Unlike relative humidity, it does not change as the air warms or cools during the day, which makes it the meteorologists preferred measure of how muggy the air actually is. This calculator uses the widely used Magnus-Tetens approximation with coefficients a equal to 17.27 and b equal to 237.7 degrees Celsius, accurate to a fraction of a degree across normal weather conditions. Enter the current air temperature and the relative humidity, pick Celsius or Fahrenheit, and read the dew point along with a plain language comfort description, since dew points above roughly 20 degrees Celsius feel oppressive to most people. All math happens locally in your browser, so the result is instant and private.
How to use Dew Point Calculator
- Enter the air temperature.
- Enter the relative humidity percentage.
- Read the dew point temperature.
- Read the comfort level tied to that dew point.
Frequently asked questions
How is dew point found from temperature and humidity?
It applies the Magnus-Tetens formula, solving for the temperature at which the air would be fully saturated given your temperature and relative humidity.
What does a high dew point feel like?
A dew point above about 20 degrees Celsius feels muggy and oppressive, while a dew point in the low teens feels comfortable, since dew point tracks the actual moisture in the air.
How is dew point different from relative humidity?
Relative humidity is a percentage relative to temperature, while dew point is an absolute temperature that does not change as the air warms or cools during the day.
What is Dew Point Calculator?
The dew point is the temperature to which air must cool, at constant pressure, for water vapor to start condensing into dew, fog or clouds. Unlike relative humidity, it does not change as the air warms or cools during the day, which makes it the meteorologists preferred measure of how muggy the air actually is.
Is Dew Point Calculator free to use?
Yes. Dew Point Calculator is completely free, with no sign-up and no usage limits.
Does Dew Point Calculator work in a web browser?
Yes. Dew Point Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with Dew Point Calculator?
Yes. Dew Point Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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