Dew Point RH Calculator

Dew Point Formula (Magnus):

\[ T_d = \frac{b \times \gamma}{a - \gamma} \] \[ \gamma = \ln\left(\frac{RH}{100}\right) + \frac{a \times T}{b + T} \]

Dew Point Temperature:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a Dew Point Calculator?

Definition: This calculator estimates the dew point temperature based on air temperature and relative humidity using the Magnus formula.

Purpose: It helps determine when moisture will condense from air, important for HVAC, construction, and weather forecasting.

2. How Does the Calculator Work?

The calculator uses the Magnus formula:

\[ T_d = \frac{b \times \gamma}{a - \gamma} \] \[ \gamma = \ln\left(\frac{RH}{100}\right) + \frac{a \times T}{b + T} \]

Where:

\( T_d \) — Dew point temperature (°C)
\( T \) — Air temperature (°C)
\( RH \) — Relative humidity (%)
\( a \) — Constant (17.27)
\( b \) — Constant (237.7)

Explanation: The formula approximates the relationship between temperature, humidity, and dew point.

3. Importance of Dew Point Calculation

Details: Knowing the dew point helps prevent condensation problems, mold growth, and material damage in buildings.

4. Using the Calculator

Tips: Enter the air temperature in °C and relative humidity (0-100%). The calculator will determine the dew point temperature.

5. Frequently Asked Questions (FAQ)

Q1: What is dew point?
A: The temperature at which air becomes saturated with water vapor and condensation begins.

Q2: Why does dew point matter in construction?
A: It helps determine when condensation will occur on surfaces, which can lead to moisture problems.

Q3: How accurate is the Magnus formula?
A: It's accurate to within ±0.4°C for temperatures between -40°C and 50°C.

Q4: What if the dew point equals the temperature?
A: This means 100% relative humidity - the air is fully saturated.

Q5: Can I calculate frost point with this?
A: For temperatures below 0°C, the result indicates frost point rather than dew point.