Vapor Pressure Deficit Calculator

Formula

The formula to calculate the vapor pressure deficit is:

\[ VPD = SVP - AVP \]

Where:

VPD is the vapor pressure deficit
SVP is the saturated vapor pressure
AVP is the actual vapor pressure

Alternatively, using relative humidity:

\[ VPD = SVP \times \left(1 - \frac{RH}{100}\right) \]

Where:

RH is the relative humidity (%)

What is Vapor Pressure Deficit?

A vapor pressure deficit, or VPD for short, is the difference between the saturated vapor pressure and the actual current vapor pressure. The saturated vapor pressure is the maximum amount of water vapor a body of air at a given temperature can hold.

Example Calculation

Example 1:

Saturated Vapor Pressure (SVP): 30
Actual Vapor Pressure (AVP): 20

Step 1: Calculate the vapor pressure deficit:

\[ VPD = 30 - 20 = 10 \]

Example 2:

Saturated Vapor Pressure (SVP): 40
Relative Humidity (RH): 50%

Step 1: Calculate the vapor pressure deficit using RH:

\[ VPD = 40 \times \left(1 - \frac{50}{100}\right) = 40 \times 0.5 = 20 \]