Relative Humidity Calculator Online

Last updated on by Editorial Staff

Relative Humidity Calculator

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Quick Guide to Use this Calculator

  • Enter the dew temperature (T(d)) in the provided input field.
  • Select the corresponding unit (Celsius, Fahrenheit, or Kelvin).
  • Enter the air temperature (T(w)) in the provided input field.
  • Select the corresponding unit (Celsius, Fahrenheit, or Kelvin).
  • (Note: need to choose the same unit for both temperatures)
  • Click the “Calculate” button to obtain the relative humidity result.
  • The result will be displayed, along with a step-by-step calculation breakdown.
  • Use the “Reset” button to clear the input fields and calculation results.


RH = 100 {e^[17.625 x T(d)/243.04+T(d)]/ e^[17.625 x T(a)/243.04+T(a)]}

Where RH is relative humidity

  e = exponential value = 2.7182818284590452353602874713527

T(d) = dew temperature

T(a) = air temperature

What is Relative Humidity?

Relative humidity is the proportion of the partial pressure of water vapor in the air to the maximum potential water vapor pressure at a specific temperature. Represented as a percentage, it serves as an indicator of how near the air is to reaching saturation with moisture.

Benefits of Using This Calculator

  • Quick and accurate calculation of relative humidity.
  • Facilitates weather forecasting and analysis.
  • Supports informed decision-making in agriculture and irrigation.
  • Optimizes HVAC systems for comfort and efficiency.
  • Enhances understanding of environmental conditions.

To whom is this calculator helpful and How?

The Relative Humidity Calculator is useful for individuals working in fields such as meteorology, agriculture, HVAC (Heating, Ventilation, and Air Conditioning), and various scientific and environmental applications. Here are some scenarios and target audiences for whom this calculator may be helpful:

Meteorologists: Meteorologists often need to calculate relative humidity as part of weather forecasting. This calculator can assist them in determining the relative humidity based on dew temperature and air temperature.

Agricultural Professionals: Farmers and agricultural scientists may use this calculator to assess the humidity levels, which can influence crop growth, disease development, and irrigation decisions.

HVAC Professionals: Professionals in the HVAC industry may find this calculator useful to understand humidity levels in indoor environments, helping them optimize heating and cooling systems for comfort and efficiency.

Environmental Scientists: Environmental researchers and scientists studying climate patterns, ecology, and environmental conditions may use this calculator to analyze humidity data.

Educational Purposes: This calculator is useful for Students and educators in meteorology, environmental science, or related fields as a learning tool.


What is Dew Temperature (T(d))?

Dew temperature occurs as the air becomes saturated with moisture, causing water vapor to condense into dew. As the air cools, it reaches a critical point where its capacity to retain moisture diminishes, leading to the formation of dew on various surfaces such as grass or car windows.
The dew temperature is a crucial factor in meteorology, agriculture, and environmental science, as it indicates the point at which dew or frost may form.

What is air temperature (T(a))?

Air temperature is the measure of the warmth or coldness of the air in a specific location at a given moment. It is a key parameter in weather forecasting, climate studies, and various industries. Air temperature influences weather patterns, the behavior of gases in the atmosphere, and the comfort levels of living organisms.

How does relative humidity affect weather conditions?

Relative humidity influences cloud formation, precipitation, and overall atmospheric stability. High humidity can lead to the formation of clouds and potentially precipitation.

Can this calculator be used for indoor environments?

Yes, HVAC professionals can use this calculator to assess and control indoor humidity levels for optimal comfort and energy efficiency.

Is there a maximum limit to relative humidity?

Yes, Relative humidity is capped at 100%, representing fully saturated air.


The Relative Humidity Calculator is a valuable tool for various professionals and enthusiasts, providing quick and precise calculations for understanding humidity levels. Whether for weather forecasting, agricultural planning, HVAC optimization, or educational purposes, this calculator enhances decision-making and insights into environmental conditions.