Dew Point Calculator
Find the dew point — the temperature air must cool to for dew to form — and see how muggy or comfortable that actually feels, from air temperature and relative humidity.
Enter the air temperature and relative humidity to find the dew point and how muggy the air feels.
Dew point comfort scale
| Comfort level | Dew point range | Description |
|---|---|---|
| Dry | < 10°C | Air feels crisp and dry, with little to no humidity discomfort. |
| Comfortable | 10–16°C | Pleasant humidity levels most people find comfortable. |
| Slightly sticky | 16–18°C | Noticeable humidity begins; skin may feel slightly damp. |
| Uncomfortable | 18–21°C | Humidity is noticeably uncomfortable for most people, especially with activity. |
| Oppressive | 21–24°C | Very humid and muggy; most people find this unpleasant. |
| Miserable | ≥ 24°C | Extremely oppressive, tropical-level humidity. |
Sources
- NWS Heat Index
- NWS Wind Chill Chart
- Dew point calculated with the Magnus-Tetens formula (Alduchov & Eskridge, 1996)
These are general weather calculations based on standard meteorological formulas, not official warnings. For severe-weather alerts, always check your local National Weather Service or meteorological agency.
About the Dew Point Calculator
The dew point is the temperature air would need to cool to, at constant pressure, for it to become fully saturated with water vapor and start forming dew or condensation. Unlike relative humidity, which is relative to the current air temperature and can swing wildly through the day even as the actual moisture in the air stays constant, dew point tracks the absolute amount of water vapor directly, which is why meteorologists consider it a more reliable measure of how muggy the air actually feels. This calculator uses the Magnus-Tetens approximation with the Alduchov & Eskridge (1996) coefficients, a standard, widely used formula for converting temperature and relative humidity into dew point. The result is matched against a six-level comfort scale, from dry to miserable, commonly used in weather reporting.
How to use this calculator
- 1 Enter the current air temperature using the slider or the number field.
- 2 Enter the relative humidity as a percentage.
- 3 Read the dew point result and its comfort-level rating, then check the reference table for the full scale.
How the dew point (Magnus-Tetens) formula works
The Magnus-Tetens approximation calculates dew point from temperature and relative humidity in two steps: γ = ln(RH / 100) + (b · T) / (c + T) Td = (c · γ) / (b - γ) where T is the air temperature in °C, RH is the relative humidity in percent, and b = 17.625, c = 243.04°C are the Alduchov & Eskridge (1996) coefficients. When the air is fully saturated (RH = 100%), the dew point equals the air temperature exactly, since the air is already holding as much moisture as it can. For example, 25°C at 50% relative humidity gives a dew point of about 13.9°C, which is comfortable, while 30°C at 80% humidity gives about 26.2°C, which is miserable — even though the air temperature itself is only 5°C higher.
Frequently asked questions
What dew point is comfortable?
A dew point under 10°C (50°F) feels dry and crisp, and 10–16°C (50–61°F) is generally considered the most comfortable range. From 16–18°C (61–64°F) it starts to feel slightly sticky, 18–21°C (64–70°F) is noticeably uncomfortable for most people, 21–24°C (70–75°F) is oppressive, and above 24°C (75°F) is considered miserable, tropical-level humidity, regardless of what the air temperature itself reads.
What's the difference between dew point and relative humidity?
Relative humidity is the amount of moisture in the air relative to the maximum it could hold at the current temperature, so it changes constantly through the day as temperature rises and falls, even if the actual moisture content stays the same. Dew point measures the absolute moisture content directly as a temperature, so it stays roughly constant through the day unless air actually moves in or out, making it a much steadier and more meaningful indicator of how humid it really feels.
Can the dew point be higher than the air temperature?
No — the dew point can never exceed the current air temperature. When relative humidity is 100%, the dew point equals the air temperature exactly, because the air is already saturated. If a weather report shows a dew point that appears higher than the temperature, one of the two readings was measured at a different time or location.
Why do meteorologists prefer dew point over humidity percentage for comfort?
Because relative humidity alone doesn't tell you how much moisture is actually in the air — 90% humidity at 5°C is barely noticeable, while 50% humidity at 35°C is stifling, since warmer air can hold far more water vapor for the same percentage reading. Dew point measures the actual moisture content as a temperature, so a given dew point feels roughly the same regardless of the air temperature, which is why weather forecasts increasingly report it alongside or instead of relative humidity.
Related tools
Dew point is the third piece of the feels-like picture — pair it with the heat index calculator for how humidity affects summer heat, and the wind chill calculator for how wind affects winter cold. The temperature converter handles direct °C/°F/kelvin conversions for any other use.