💦 Evaporation Rate Calculator
Estimate the rate of water evaporation from an open surface (like a pool or reservoir) using a simplified empirical formula.
What This Calculates
This calculator estimates how quickly water evaporates from an open surface, such as a pool, pond, or reservoir, based on temperature, humidity, and wind — the main environmental drivers of evaporation.
The Method
It uses a mass-transfer style approach: saturation vapor pressures at the water surface and air are computed with the Magnus formula, and the vapor pressure deficit is combined with a wind-speed function (loosely based on Meyer’s formula) to estimate the evaporation rate in mm/day, then scaled by surface area.
Note: real-world evaporation also depends on solar radiation, water depth, and local microclimate; this is a general planning estimate, not a precision measurement.