Abstract: Crop coefficients and reference crop evapotranspiration must be determined in order to estimate irrigation water requirements for any crop and improve irrigation scheduling and water management. The objective of this study is to evaluate the crop water requirements of cotton using the FAO-56 Penman-Monteith Method with dual crop coefficients. Meteorological data for the Unchadi Section Command Area of Shetrunji Right Bank Main Canal, such as maximum and minimum temperatures, mean relative humidity, sunlight hours, and wind speed, are used to calculate reference crop evapotranspiration. The MABIA method in WEAP (Water Evaluation And Planning) software uses the dual-Kc approach to calculate crop evapotranspiration or crop water requirement, which is described in FAO Irrigation and Drainage Paper No. 56, whereby the Kc value is divided into a ‘basal’ crop coefficient (Kcb) and a separate component (Ke) representing evaporation from the soil surface. The basal crop coefficient represents actual ET conditions when the soil surface is dry but sufficient root zone moisture is present to support full transpiration. Cotton crop water requirement (ETc) using is found about 940.93 mm during the growing season in region. This result can be useful for agricultural planning and efficient irrigation management for cotton cultivation in Unchadi Section Command Area of Shetrunji Right Bank Main Canal.