Accurate estimation of evapotranspiration in a paddy field is crucial for efficient water management. Researchers in Japan determined crop and soil evaporation coefficients using actual measurements in a rice paddy field. They found that evapotranspiration varied during different growth stages, with average values ranging from 4.4 mm/d to 7.4 mm/d. Evaporation was low and consistent when the leaf area index reached 3. By applying specific crop coefficients for each growth stage, they accurately estimated daytime evapotranspiration. Additionally, a simple model using leaf area index was developed to predict soil water evaporation, which proved to be effective.