Disclaimer: This dew point calculator is provided for educational and informational purposes only. Results are estimates based on common meteorological equations and may vary from professional weather-station outputs due to sensor accuracy, calibration, airflow, and local microclimate effects. Do not rely on this tool as the sole basis for safety-critical decisions.

The Dew Point Calculator helps you estimate the dew point (°C) from two simple inputs: air temperature and relative humidity (RH). Dew point is the temperature at which air becomes saturated with water vapor and condensation begins to form. In practical terms, dew point is one of the most intuitive indicators of “how humid it feels” and how likely moisture is to condense on surfaces.

Why Dew Point Matters

Dew point is widely used in weather forecasting, HVAC and building comfort, greenhouse management, irrigation planning, and outdoor activity safety. When the dew point is close to the current air temperature, the air is nearly saturated and fog, dew, or condensation becomes more likely. In agriculture and gardening, a higher dew point can signal conditions favorable for certain plant diseases (because leaf surfaces stay wet longer), while in indoor environments it can indicate increased risk of condensation on windows or cold walls.

How to Use This Dew Point Calculator

1. Enter the air temperature in degrees Celsius (°C).
2. Enter the relative humidity as a percentage (%).
3. Click calculate to receive the estimated dew point (°C).

If you are measuring temperature and humidity with a sensor, ensure the sensor is not exposed to direct sunlight, heaters, or localized moisture sources, as these can skew readings and affect the dew point estimate.

How Dew Point Is Calculated

This calculator typically uses a well-known approximation (often referred to as the Magnus or Magnus-Tetens formula) that converts temperature and relative humidity into an estimated dew point. The calculation involves the saturation vapor pressure at the given temperature and the actual vapor pressure derived from RH. While the underlying math is straightforward, the dew point is highly sensitive to input accuracy—small changes in humidity can noticeably change the resulting dew point.

Interpreting Your Dew Point Result

• Low dew point generally indicates drier air and faster evaporation.
• Moderate dew point suggests comfortable humidity for many people and many crops.
• High dew point indicates moist air, slower evaporation, and greater risk of condensation.

For comfort discussions, dew point is often preferred over relative humidity because it remains more stable across temperatures and better reflects the actual moisture content of the air.

Common Applications

• HVAC & indoor comfort: anticipate condensation risk and optimize dehumidification.
• Greenhouses: monitor moisture conditions to reduce fungal pressure and manage ventilation timing.
• Gardening & irrigation: understand evaporation potential and humidity stress on plants.
• Weather planning: assess fog/dew likelihood and perceived “mugginess.”

FAQ

Is dew point the same as relative humidity?
No. Relative humidity is a ratio that changes with temperature. Dew point is an absolute humidity indicator: it tells you the temperature at which condensation begins.

Why does my dew point seem “too high” or “too low”?
Check that your temperature is in °C and humidity is entered as a percentage. Also consider sensor placement, airflow, and calibration.

Can I use this for scientific or compliance reporting?
For regulated reporting, use calibrated instruments and validated methods. This tool is best for planning, learning, and quick estimates.