Enter the partial pressure of water vapor and the total pressure into the calculator to determine the specific humidity.

Specific Humidity Formula

The following equation can be used to calculate a specific humidity.

SH = (.622 * P / ( P - Pw ) ) * 100
  • Where SH is the specific humidity (%)
  • P is the total pressure
  • PW is the partial pressure of water vapor

To calculate specific humidity, divide the total pressure by the result of the total pressure minus the partial pressure, then multiply by .622, then multiply again by 100.

Specific Humidity Definition

Specific humidity is defined as the ratio of the humidity of the air to the absolute water vapor pressure of the air.

Specific Humidity Example

How to calculate specific humidity?

  1. First, determine the total pressure.

    Meausre the total pressure of the air.

  2. Next, determine the water vapor pressure.

    Calculate the partial pressure of water vapor.

  3. Finally, calculate the specific humidity.

    Using the equation above, calculate the specific humidity.


What is specific humidity?

Specific humidity is a measure of the humidity of air with respect to the ratio of the water vapor pressure to the total pressure.

What is the partial pressure of water vapor?

The partial pressure of water is the pressure that the water vapor contributes to the overall pressure of the air.