Evapotranspiration (ET) is the sum of evaporation and transpiration from the surface to the atmosphere. ET is a hydrologic cycle component and importance in agricultural water management such as schedules of irrigation water requirement, irrigation system design and watershed management. Evapotranspiration can be measured or estimated using several methods. The objectives of this study were simple methods and quick analyses for the estimating of crop coefficients (K_c) and daily actual evapotranspiration (ET_a) from Normalized Difference Vegetation Index (NDVI) derived from Landsat 8 and Sentinel-2 satellite images. Subsequent comparison of ET_a from both satellite images at Ban Nong Bua, Amphoe Ban Fang, Khon Kaen Province, Thailand. The results showed that good correlation between NDVI and ET_a from both satellite images (coefficient of determination (R²) = 0.85 and 0.87, respectively). Both satellite images can be used or combined to detect temporal and spatial analysis. Sentinel-2 can provide more fine resolution of 10 m in VIS-NIR bands than Landsat 8 and is suitable for precision farming or site specific management, while Landsat 8 TIRS bands were advantages.