Enter the temperature, relative humidity, and wind speed into the calculator to determine the evaporation potential. This calculator helps estimate the amount of water that can evaporate from a surface under specific weather conditions.

Evaporation Potential Formula

The following formula is used to estimate the evaporation potential.

EP = (25 + 19 * WS) * (0.5 + 0.54 * T) * (1 - RH / 100)


  • EP is the evaporation potential (mm/day)
  • T is the temperature (°C)
  • RH is the relative humidity (%)
  • WS is the wind speed (m/s)

To estimate the evaporation potential, multiply the sum of 25 and 19 times the wind speed by the sum of 0.5 and 0.54 times the temperature, and then multiply by one minus the relative humidity divided by 100.

What is Evaporation Potential?

Evaporation potential is a measure of the ability of the atmosphere to remove water from the surface through the process of evaporation. It is influenced by factors such as temperature, humidity, and wind speed. Understanding evaporation potential is important for water resource management, agriculture, and climate studies.

How to Calculate Evaporation Potential?

The following steps outline how to calculate the Evaporation Potential.

  1. First, determine the temperature (T) in degrees Celsius.
  2. Next, determine the relative humidity (RH) as a percentage.
  3. Next, determine the wind speed (WS) in meters per second.
  4. Next, gather the formula from above = EP = (25 + 19 * WS) * (0.5 + 0.54 * T) * (1 – RH / 100).
  5. Finally, calculate the Evaporation Potential (EP) in millimeters per day.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Temperature (T) = 30°C

Relative Humidity (RH) = 50%

Wind Speed (WS) = 3 m/s