Dew Point Calculator – Calculate Dew Point from Temperature & Humidity

Calculate the dew point temperature instantly with our free Dew Point Calculator. Enter air temperature and relative humidity to determine when condensation will form — useful for weather forecasting, HVAC, and agriculture.

Weather Conditions

Air Temperature

Relative Humidity (%)

Dew point is the temperature at which air becomes saturated and water vapor condenses into liquid water.

Results

Enter temperature and humidity to calculate dew point

Dew Point Comfort Guide

Dew Point	Comfort Level	Description
Below 50°F	Dry/Comfortable	Very comfortable, dry air
50-60°F	Comfortable	Most people feel comfortable
60-65°F	Slightly Humid	Starting to feel humid
65-70°F	Humid	Uncomfortable for most people
70-75°F	Very Humid	Very uncomfortable, oppressive
Above 75°F	Extremely Uncomfortable	Dangerous for sensitive individuals

How to Use This Dew Point Calculator

Enter the air temperature

Type the current air temperature in Fahrenheit or Celsius. This is the ambient temperature you measure with a thermometer.

Input the relative humidity percentage

Enter the relative humidity as a percentage (0-100%). You can find this from a weather app or hygrometer.

Read your dew point and comfort level

The calculator instantly shows the dew point temperature and tells you how humid it feels. Use this to plan outdoor activities or check for condensation risk.

Dew Point and Relative Humidity Reference

Dew Point Range	Comfort Level	What It Feels Like
Below 50 F (10 C)	Dry/Comfortable	Crisp, dry air. Very comfortable for most people.
50-59 F (10-15 C)	Comfortable	Pleasant humidity. Most people feel comfortable.
60-64 F (16-18 C)	Slightly Humid	Starting to feel sticky. Noticeable moisture in the air.
65-69 F (18-21 C)	Humid	Uncomfortable for many people. Air feels heavy.
70-74 F (21-23 C)	Very Humid	Oppressive. Difficult to cool down through sweating.
75 F+ (24 C+)	Extremely Uncomfortable	Dangerous for sensitive individuals. Avoid strenuous activity.

Understanding Dew Point

Dew point is the temperature at which air becomes saturated with water vapor and condensation begins. Unlike relative humidity, dew point is an absolute measure of moisture in the air — it doesn't change with temperature.

Why Dew Point Matters More Than Humidity

Relative humidity changes with temperature even when moisture stays the same. A 90 F day at 50% humidity feels different than a 70 F day at 50% humidity. Dew point stays constant, making it a better indicator of how humid it actually feels. A dew point of 65 F feels humid whether it's 75 F or 95 F outside.

How Condensation Forms

When air cools to its dew point temperature, it can no longer hold all its water vapor. The excess condenses into liquid water. This is why you see dew on grass in the morning — the ground cooled overnight, dropping the air temperature to the dew point. It's also why cold drinks sweat on a hot day.

The Magnus Formula

This calculator uses the Magnus formula, a widely accepted approximation for dew point. The formula relates temperature, relative humidity, and dew point through empirical constants. It's accurate for typical atmospheric conditions between -40 C and 50 C.

Dew Point and Weather Forecasting

Meteorologists use dew point to predict fog, frost, and precipitation. When the air temperature and dew point are within a few degrees, fog is likely. If the dew point is above freezing and the temperature drops to meet it, you get rain. If both are below freezing, you get frost or snow.

Common Dew Point Scenarios

Scenario	Temperature	Relative Humidity	Dew Point
Desert day	95 F	15%	~35 F (very dry)
Comfortable spring	72 F	50%	~52 F (pleasant)
Summer afternoon	85 F	60%	~70 F (humid)
Tropical day	90 F	75%	~81 F (oppressive)
Foggy morning	55 F	100%	55 F (saturation)
Winter indoor air	70 F	20%	~25 F (very dry)

Tips for Using Dew Point Data

Plan Outdoor Activities Around Dew Point

For exercise or outdoor work, aim for dew points below 60 F. Above 70 F, take frequent breaks and stay hydrated. Above 75 F, consider postponing strenuous activity.

Prevent Condensation in Your Home

If your window surface temperature drops below the indoor dew point, condensation forms. In winter, keep indoor humidity lower (30-40%) to prevent window condensation and mold growth.

Know When Frost Is Likely

If the dew point is at or below freezing and the forecast low is near or below the dew point, expect frost. This matters for gardeners even when the air temperature stays above 32 F.

HVAC Sizing and Dew Point

High dew points mean your AC has to work harder to remove moisture. In humid climates, proper dehumidification matters as much as cooling capacity for comfort.

Frequently Asked Questions

What is a comfortable dew point?

Most people feel comfortable with dew points between 50 F and 59 F (10-15 C). Below 50 F feels dry and crisp. Above 60 F starts feeling humid. Above 70 F feels oppressive to most people.

Can dew point be higher than temperature?

No. Dew point cannot exceed air temperature. When they're equal, relative humidity is 100% and condensation occurs. If you see a reading where dew point appears higher, it's a measurement error.

What causes high dew points?

High dew points come from moisture in the air. Sources include evaporation from bodies of water, transpiration from plants, and moist air masses moving in from tropical regions. Gulf Coast states often see dew points above 70 F in summer.

How does dew point affect health?

High dew points make it harder for sweat to evaporate, reducing your body's ability to cool itself. This increases heat stress risk. People with respiratory conditions may also find high humidity uncomfortable. Low dew points (dry air) can irritate skin and airways.

Why does my car fog up?

Your breath adds moisture to the car's air, raising the dew point. When that moist air hits cold windows, it cools below the dew point and condenses. Running the AC removes moisture from the air, lowering the dew point and clearing the fog.

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