Dew Point Calculator
Calculate the dew point from air temperature and relative humidity.
Try an example
55.1°F
About this calculator
How This Dew Point Calculator Works
Enter the air temperature and relative humidity, and the calculator returns the dew point — the temperature air would need to cool to for it to become fully saturated with moisture.
Worked Example
At 75°F with 50% relative humidity, the dew point is about 55.1°F — a moderate, generally comfortable humidity level.
The Formula
This calculator uses the Magnus formula, an approximation widely used in meteorology for its accuracy across typical atmospheric conditions, converting temperature to Celsius internally before computing the result and converting back to Fahrenheit for display.
Why Dew Point Beats Relative Humidity for Comfort
Relative humidity is relative — the same actual amount of moisture in the air reads as a higher percentage on a cooler day and a lower percentage on a hotter day, since warm air can hold more moisture before saturating. Dew point instead measures the actual moisture content directly, which is why meteorologists generally consider it a more reliable indicator of how humid a day will actually feel.
Reading Dew Point Comfort Levels
- Below 55°F — dry, comfortable air
- 55-65°F — noticeable humidity, still generally acceptable
- 65-70°F — muggy, uncomfortable for many people
- Above 70°F — oppressive, very humid conditions
Worked example
At 75°F with 50% relative humidity, the dew point is about 55.1°F — a moderate, generally comfortable level of humidity.
Frequently asked questions
Why is dew point a better humidity indicator than relative humidity?
Relative humidity depends on temperature (the same absolute moisture reads as a higher percentage on a cooler day), while dew point is a more direct measure of how much moisture is actually in the air — meteorologists generally consider it more useful for gauging how humid it will actually feel.
What dew point levels feel comfortable versus muggy?
Roughly: below 55°F feels dry and comfortable, 55-65°F feels noticeable but acceptable, and above 65°F starts to feel muggy or oppressive, with 70°F+ feeling quite uncomfortable to most people.