Dew Point Calculator

Calculate the temperature at which water vapor in the air will condense into liquid water, forming dew. This calculator uses the Magnus formula to provide accurate dew point predictions based on current air temperature and relative humidity.

What is Dew Point?

Dew point is the temperature at which water vapor in the air begins to condense into liquid water, forming dew. It’s a critical measurement in meteorology and everyday life because it:

• Indicates when condensation will occur
• Helps predict fog and frost formation
• Provides a measure of atmospheric moisture content
• Affects how comfortable the weather feels

How to Use the Calculator

1. Enter the current air temperature
2. Input the relative humidity percentage (0-100%)
3. Select your preferred temperature unit (Celsius or Fahrenheit)
4. Click “Calculate” to get the dew point temperature

The calculator will display the temperature at which dew will form under the current conditions.

Understanding the Results

• If the dew point is close to the current air temperature, there’s a high chance of precipitation, fog, or dew formation
• A dew point below freezing (0°C/32°F) indicates frost formation instead of dew
• The higher the dew point, the more moisture in the air

Comfort Levels Based on Dew Point

Dew Point (°F)	Dew Point (°C)	How it Feels
< 50°F	< 10°C	Very comfortable
50-59°F	10-15°C	Comfortable
60-64°F	16-18°C	Somewhat comfortable
65-69°F	18-21°C	Slightly uncomfortable
70-74°F	21-23°C	Uncomfortable
≥ 75°F	≥ 24°C	Very uncomfortable

Common Applications

1. Weather Forecasting

   • Predicting fog formation
   • Estimating precipitation likelihood
   • Planning outdoor activities

2. Agriculture

   • Managing crop irrigation
   • Preventing frost damage
   • Controlling greenhouse conditions

3. Building Management

   • Preventing condensation
   • Managing indoor humidity
   • Controlling HVAC systems

4. Industrial Processes

   • Maintaining optimal manufacturing conditions
   • Preventing product damage
   • Managing storage environments

Technical Notes

• The calculator uses the Magnus formula for dew point calculation
• Results are accurate within ±0.4°C for:
  • Temperatures: -45°C to 60°C
  • Relative Humidity: 1% to 100%
• For temperatures below freezing, the calculator indicates frost point rather than dew point

Tips for Accurate Measurements

1. Use accurate temperature measurements
2. Ensure humidity readings are current
3. Take measurements in well-ventilated areas
4. Avoid direct sunlight or heat sources
5. Use calibrated instruments when possible

Related Concepts

• Relative Humidity: The ratio of actual water vapor pressure to the saturation vapor pressure at the current temperature
• Absolute Humidity: The actual amount of water vapor in a given volume of air
• Frost Point: Similar to dew point, but indicates when water vapor will deposit directly as frost (below freezing)
• Heat Index: How hot it feels when relative humidity is combined with air temperature