Pan Evaporation Calculator

Online pan evaporation calculator to estimate evaporation from the water surface in the pan and the evapotranspiration of the standard grass.

Determination of K pan

When using the evaporation pan to estimate the ETo, in fact, a comparison is made between the evaporation from the water surface in the pan and the evapotranspiration of the standard grass. Of course the water in the pan and the grass do not react in exactly the same way to the climate. Therefore a special coefficient is used (K pan) to relate one to the other.

The pan coefficient, K pan, depends on:

• the type of pan used
• the pan environment: if the pan is placed in a fallow or cropped area
• the climate: the humidity and windspeed