Dew Point Calculator - Calculate Dew Point Temperature

Dew Point Calculator

The Dew Point Calculator determines the temperature at which air becomes saturated with water vapor and condensation begins. It's a key indicator of humidity levels and comfort conditions.

Weather Conditions

Temperature Unit

Fahrenheit (°F)Celsius (°C)

Input Method

Temperature + Relative HumidityTemperature + Dew PointRelative Humidity + Dew Point

Air Temperature (°F)

Relative Humidity (%)

0%50%100%

Quick Examples

Dew Point Results

Dew Point Temperature

60.2°F

Air Temperature

75.0°F

Relative Humidity

60.0%

Temperature Difference

14.8°

Comfort Level

Slightly Humid

SLIGHTLY HUMID

Noticeable humidity. Still comfortable for most activities.

Dew Point Chart (°F)

Temp	30%	40%	50%	60%	70%	80%
60°F	36	41	46	49	52	55
70°F	45	50	55	59	62	65
80°F	53	59	64	68	71	75
90°F	61	68	73	77	81	84
100°F	70	76	82	86	90	94

Values show dew point in °F for different temperature and humidity combinations

How to Use the Dew Point Calculator

Step-by-Step Instructions

1. Select your preferred temperature unit (Fahrenheit or Celsius)
2. Choose your input method based on available data
3. Enter the required values (temperature, humidity, or dew point)
4. View the calculated results and comfort analysis
5. Use the chart to compare different conditions

Understanding Results

• Dew point indicates absolute humidity levels
• Higher dew points feel more humid and uncomfortable
• Temperature difference shows saturation proximity
• Comfort levels help plan activities and clothing

Understanding Dew Point

What is Dew Point?

Dew point is the temperature at which air becomes saturated with water vapor and condensation begins to form. It's a direct measure of the amount of moisture in the air.

Why It Matters

Unlike relative humidity, dew point doesn't change with temperature. It provides a consistent measure of atmospheric moisture and is better for comparing humidity levels across different temperatures.

Practical Applications

Dew point is used in weather forecasting, HVAC systems, agriculture, and comfort assessment. It helps predict fog formation, frost conditions, and human comfort levels.

Dew Point Formulas

Magnus Formula (Approximation)

Td = (b × α) / (a - α)

Where: α = ln(RH/100) + (a×T)/(b+T), a = 17.27, b = 237.7°C, T = Temperature (°C), RH = Relative Humidity (%)

Relative Humidity from Dew Point

RH = 100 × exp((a×Td)/(b+Td) - (a×T)/(b+T))

This formula calculates relative humidity when temperature and dew point are known.

Dew Point Comfort Levels

Dry (< 50°F)

Very comfortable. Low humidity levels. Ideal for most people. May cause dry skin or static electricity.

Comfortable (50-60°F)

Most comfortable range for most people. Optimal humidity levels for indoor and outdoor activities.

Humid (60-70°F)

Noticeably humid. Some people may feel uncomfortable. Increased sweating and reduced cooling efficiency.

Oppressive (> 70°F)

Very humid and uncomfortable. Tropical conditions. Difficult for body to cool itself through sweating.

Applications

Weather Forecasting

Meteorologists use dew point to predict fog, frost, and precipitation. It's more reliable than relative humidity for weather analysis.

HVAC Systems

HVAC engineers use dew point to design dehumidification systems and prevent condensation in buildings.

Agriculture

Farmers use dew point to predict disease conditions, irrigation needs, and optimal harvesting times.

Aviation

Pilots use dew point to assess visibility conditions and potential for aircraft icing.

Example Calculations

Example 1: Comfortable Day

Air Temperature: 75°F (24°C)

Relative Humidity: 50%

Dew Point: 55°F (13°C)

Comfort Level: Comfortable

Example 2: Humid Conditions

Air Temperature: 85°F (29°C)

Relative Humidity: 80%

Dew Point: 79°F (26°C)

Comfort Level: Oppressive

Frequently Asked Questions

What's the difference between dew point and relative humidity?

Dew point is an absolute measure of moisture that doesn't change with temperature, while relative humidity is a percentage that varies with temperature. Dew point is more useful for comparing moisture levels across different temperatures.

Can dew point be higher than air temperature?

No, dew point can never be higher than air temperature. When they're equal, the relative humidity is 100% and condensation occurs. The closer they are, the higher the humidity.

What dew point is considered comfortable?

Dew points between 50-60°F (10-15°C) are generally considered most comfortable. Below 50°F feels dry, while above 65°F (18°C) starts to feel humid and uncomfortable.