Relative Humidity Calculator

Calculate the relative humidity in the air using temperature and dew point measurements. This calculator helps you understand the amount of moisture in the air relative to the maximum amount it could hold at a given temperature.

Why Use This Calculator?

Relative humidity is a crucial measurement for:

• Weather monitoring and forecasting
• Indoor climate control and comfort
• Preventing mold and moisture damage
• Agricultural planning and greenhouse management
• Industrial processes and storage conditions

How to Use It

1. Enter the current air temperature in °C or °F
2. Enter the dew point temperature in the same unit
3. The calculator will instantly show the relative humidity percentage

Understanding Results

The result shows relative humidity as a percentage (0-100%):

• 0% means completely dry air
• 100% means the air is fully saturated with water vapor
• Comfortable indoor humidity typically ranges from 30-50%
• Values above 60% may feel muggy and promote mold growth

Calculation Method

This calculator uses the Magnus-Tetens formula to determine relative humidity (RH):

RH = 100 × exp((17.625 × Td)/(243.04 + Td)) / exp((17.625 × T)/(243.04 + T))

Where:

• T = Air temperature in °C
• Td = Dew point temperature in °C

Tips and Best Practices

• For accurate readings, ensure both temperatures are measured at the same location
• Take measurements away from direct heat sources or cold spots
• Use calibrated instruments for precise measurements
• Monitor trends over time rather than single readings
• Consider seasonal variations in your area

Common Use Cases

1. Home Climate Control

   • Monitor indoor comfort levels
   • Optimize HVAC settings
   • Prevent condensation issues

2. Weather Monitoring

   • Track outdoor conditions
   • Predict precipitation likelihood
   • Plan outdoor activities

3. Industrial Applications

   • Control manufacturing environments
   • Maintain storage conditions
   • Prevent corrosion and material damage

Frequently Asked Questions

What is the ideal relative humidity?

For indoor spaces, 30-50% is generally considered ideal. This range balances comfort with preventing mold growth and protecting materials.

Why does relative humidity change with temperature?

Warmer air can hold more moisture than cooler air. As temperature rises, relative humidity decreases even if the actual amount of moisture stays the same.

How does relative humidity affect comfort?

High humidity makes it harder for sweat to evaporate, making us feel warmer. Low humidity can cause dry skin and respiratory discomfort.

What’s the relationship between dew point and relative humidity?

The closer the air temperature is to the dew point, the higher the relative humidity. When they’re equal, relative humidity is 100%.