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Dew Point Calculator.
Calculate dew point, relative humidity, absolute humidity, wet-bulb temperature and vapor pressure. Switch modes to solve for any variable.
Calculate
Temp Unit
Dew Point
—
Condensation temperature
Comfort Level
—
-20°C10°C21°C35°C
Psychrometric Chart
Humidity ratio vs. temperature — locate your conditions in the atmospheric moisture field
Your conditions Dew point Wet-bulb Comfort zone RH % curves
Hover or tap the chart to read any point · click to set your conditions.
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Detailed Results
Relative Humidity
—
% of air saturation
Absolute Humidity
—
g/m³ water vapor
Wet-Bulb Temp
—
Evaporative cooling limit
Vapor Pressure
—
Partial pressure H₂O
Sat. Vapor Pressure
—
At air temperature
Formula Used
Uses the Magnus-Tetens approximation (Alduchov & Eskridge 1996 coefficients): γ = ln(RH/100) + 17.625·T / (243.04 + T). Wet-bulb uses Stull's (2011) empirical formula. Valid for −20°C to 50°C, 5–99% RH.
About Dew Point
What is dew point?
The dew point is the temperature at which a given parcel of air must be cooled, at constant pressure, for water vapor to condense into liquid water. When air temperature falls to the dew point, relative humidity reaches 100% and dew, fog, or clouds form.
Dew point vs relative humidity
Relative humidity changes whenever the temperature changes — even if the actual moisture content stays the same. Dew point is an absolute measure of moisture: a dew point of 20°C means the same amount of water vapor whether the air temperature is 25°C or 35°C. Meteorologists prefer dew point for this reason.
Comfort guide
Dew points below 10°C feel dry and crisp. Between 10–16°C is comfortable. Above 18°C starts to feel sticky. Above 21°C (70°F) is oppressive for most people. Above 24°C can be dangerous for prolonged outdoor activity.
Related Calculators
Tips
- →Switch modes to solve for any one of the three variables.
- →A dew point above 21°C (70°F) feels oppressive to most people.
- →Dew point cannot exceed air temperature (RH would exceed 100%).
- →Use Share to copy a link with your values pre-filled.