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.
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.
Yes. Dew Point Calculator is completely free, with no sign-up and no usage limits.
Yes. Dew Point Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Dew Point Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.