Humidity Converter
Convert between relative humidity, absolute humidity, specific humidity, dew point, and vapor pressure.
Definition: Absolute humidity is the mass of water vapour per unit volume of air, expressed in g/m³. Relative humidity is the ratio of the actual vapour pressure to the saturation vapour pressure at the same temperature, expressed as a percentage.
Relative Humidity Calculator
RH is relative humidity; AH is vapor mass per volume; q is vapor mass per total moist-air mass. q differs from the mixing ratio (vapor mass per dry-air mass). The saturation equations follow Ambaum (2020), with MetPy 1.7.1 constants and explicit liquid/ice selection. The numerical input range is −80 to +50 °C; subzero liquid-water results are a model extrapolation, not an accuracy guarantee. A zero RH has no finite dew point; dew/frost points below −80 °C are outside the display range. MetPy
Humidity Level Reference
Comfort Level
Current Status
About Humidity
- Relative Humidity: Moisture in air vs maximum capacity
- Dew Point: Temperature where air becomes saturated
- Ideal Indoor: 30% - 50% relative humidity
How to Use the Humidity Calculator
Enter Temp
Input the current temperature in Celsius
Enter Humidity
Input relative humidity percentage (0-100%)
View Dew Point
See calculated dew point temperature
Check Comfort
Use reference guide for comfort levels
Understanding Humidity & Dew Point
What is Dew Point?
Dew point is the temperature at which air becomes saturated with water vapor, causing dew to form. It's a more accurate measure of atmospheric moisture comfort than relative humidity alone.
- • Relative Humidity: Percentage of moisture in air vs capacity
- • Dew Point: Temperature where condensation occurs
- • Comfort Index: How humidity affects human comfort
- • Health Impact: Effects on respiratory conditions
Why Monitor Humidity?
Proper humidity levels are crucial for health, comfort, and preserving property. Too dry causes irritation and damage; too humid promotes mold and discomfort.
- • Health: Humidity preferences vary; indoor moisture control does not guarantee health protection
- • Home Comfort: Prevent muggy or dry indoor conditions
- • Property Protection: Avoid mold or excessive dryness damage
- • Weather Planning: Understand outdoor comfort conditions
Instant Calculation
Real-time dew point calculation as you enter values.
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Humidity Conversion Formulas
Dew point / frost point: inverse vapor pressure
Saturation pressure uses the selected water or ice model from Ambaum (2020), equations 13 and 17, with constants matching MetPy 1.7.1. The point is solved numerically from the same model. Water gives dew point; ice gives frost point. Zero vapor pressure has no finite point. Points below the supported −80 °C calculation range are not reported; this is not an instrument accuracy guarantee.
Where T is air temperature in °C, RH is relative humidity in %, and a = 17.27 and b = 237.7 °C are Magnus coefficients. The formula is accurate to within about 0.35 °C for temperatures from −40 °C to +50 °C, which covers virtually all practical weather and indoor conditions.
Absolute Humidity
Absolute humidity is the water vapor mass per volume of air. e is vapor pressure in pascals, Rv ≈ 461.52 J/(kg·K), and T is temperature in Celsius. RH is defined relative to saturation over the selected phase.
Specific Humidity & Vapor Pressure
Specific humidity q is water vapor mass divided by total moist air mass. P and e must use the same pressure unit. Do not confuse q with dry-air mixing ratio εe/(P−e). Change P to the pressure at your location; 1013.25 hPa is a reference value. Heating without adding or removing moisture changes RH, while q remains constant.