Dew Point Calculator
Calculate Dew Point values for science, physics, chemistry, and engineering problems.
This dew point calculator finds the dew point - the temperature air would need to cool to for water vapor to begin condensing - from the current air temperature and relative humidity, a key measure of how humid the air actually feels.
Enter the air temperature and relative humidity, and the calculator returns the dew point.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| 77°F air temperature, 60% relative humidity | Dew point ≈ 62°F | Using the Magnus-Tetens approximation at 25°C and 60% RH gives a dew point of about 16.7°C ≈ 62°F - in the "somewhat humid" comfort range. |
| 86°F air temperature, 80% relative humidity | Dew point ≈ 79°F | At 30°C and 80% RH, the same approximation gives a dew point of about 26.2°C ≈ 79°F - in the "oppressive" range, despite the air temperature itself not being unusually extreme. |
What Dew Point Actually Measures
Unlike relative humidity, which is temperature-dependent, dew point directly reflects the actual amount of moisture in the air - a higher dew point always means more moisture present, regardless of the current air temperature, which makes it a more consistent way to compare humidity conditions across different temperatures.
Reading Dew Point Comfort Levels
Dew points below 55°F generally feel comfortable, 55-65°F feels somewhat humid, 65-75°F feels muggy and uncomfortable, and above 75°F feels oppressive - unlike relative humidity percentages, these dew point ranges mean roughly the same thing regardless of the day's actual air temperature.
How to Use the Dew Point Calculator
- Open the Dew Point Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the dew point calculator works.
Frequently Asked Questions
What is the difference between dew point and relative humidity?
Relative humidity is temperature-dependent and shows how close air is to saturation at the current temperature, while dew point directly reflects the actual moisture content in the air, independent of temperature - making dew point a more consistent comfort indicator.
What dew point is considered comfortable?
Dew points below about 55°F generally feel comfortable to most people, while values above 65-70°F tend to feel increasingly muggy or oppressive.
Can dew point be higher than air temperature?
No - dew point can never exceed the current air temperature, since dew point represents the temperature air would need to cool to in order to reach saturation, and it equals air temperature only when relative humidity is 100%.
How do I use this dew point calculator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the Dew Point Calculator calculate?
Calculate Dew Point values for science, physics, chemistry, and engineering problems. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this dew point use?
The formula is: Dew Point ≈ f(Temperature, Relative Humidity) — Magnus-Tetens approximation. The underlying relationship between vapor pressure and temperature was described by German physicist Gustav Magnus in 1844, later refined into the practical approximation still commonly used today by Dutch meteorologist Otto Tetens in 1930. Meteorologists generally prefer dew point over relative humidity as a comfort indicator specifically because dew point directly reflects absolute moisture content, while humidity percentage is relative to (and therefore misleading across) different air temperatures.
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Last updated: September 27, 2026.