Dew Point Calculator
Enter the air temperature and relative humidity to find the dew point.
How dew point is calculated
This calculator uses the Magnus formula, a widely used approximation that relates air temperature and relative humidity to the dew point — the temperature air would need to cool to for water vapor to begin condensing, given its current moisture content.
The dew point is a more useful measure of how humid the air actually feels than relative humidity alone, since relative humidity changes with temperature even when the actual moisture content of the air stays the same.
Frequently asked questions
What does a high dew point mean?
A higher dew point means more moisture is actually present in the air, which generally feels more humid and uncomfortable. A dew point above about 65°F (18°C) is commonly considered to feel muggy, and above 75°F (24°C) is considered oppressive.
Why is dew point a better humidity indicator than relative humidity?
Relative humidity is a percentage relative to the air's maximum moisture capacity at the current temperature, so it changes throughout the day even if the actual moisture in the air stays constant. Dew point reflects the absolute moisture content directly, making it more consistent.
Can the dew point be higher than the air temperature?
No — the dew point can never exceed the current air temperature. When the air temperature equals the dew point, the relative humidity is 100% and condensation (like dew, fog, or clouds) begins to form.