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Dew Point Calculator

Estimate dew point from Celsius air temperature and relative humidity.

Dew Point Calculator Inputs

Results computed instantly — your data never leaves your device.

Dew Point Calculator Results

Real-Time

Dew point

12.0 °C

Applicability

Magnus approximation for entered Celsius/RH

100% Client-SidePrivate & Secure

How to Use the Dew Point Calculator

  1. 1

    Enter air temperature in °C.

  2. 2

    Enter relative humidity.

  3. 3

    Review the dew-point approximation.

  4. 4

    Use a calibrated instrument for critical humidity or condensation work.

Formula & Mathematical Basis

Magnus approximation: γ = ln(RH/100) + (17.625T)/(243.04+T); dew point = 243.04γ/(17.625−γ).

Variable Key

T

Air temperature in °C

RH

Relative humidity in percent

📝 The route clamps humidity to a small positive value to avoid logarithm errors and reports an approximation.

Step-by-Step Examples

1

Indoor humidity estimate

Scenario: 20°C and 60% relative humidity.

  1. 1.Calculate the Magnus intermediate γ.
  2. 2.Substitute γ into the dew-point expression.
  3. 3.Keep temperature in Celsius.
  4. 4.Review approximately 12°C.
✅ Dew point is approximately 12.0°C.

Practical Use Cases

  • Estimate condensation-related dew point.
  • Explain the connection between temperature and humidity.

Common Pitfalls

  • Entering Fahrenheit while the route expects Celsius.
  • Treating relative humidity percent as a decimal.
  • Using dew point as a direct mold or building diagnosis.

Frequently Asked Questions

Does a high dew point always mean condensation?

No; surface temperature and local conditions also matter.

Is this a weather-station replacement?

No; it is a formula estimate from entered values.

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