Abstarct: Iran, with an average annual long-term precipitation of approximately 206 mm and a per capita water availability of about 1600 m3/year, is classified as an arid and semi-arid country, constantly facing drought and water scarcity. The agricultural sector consumes the largest share of water in the country. Greenhouses represent one of the best management approaches for optimizing the use of existing water and soil resources, and along with improved irrigation efficiency, they can play a significant role in water consumption management. Calculating the water requirements and virtual water content of a crop is the primary step towards optimal irrigation planning. The main objective of this research is to use field methods to calculate the water requirements of plants, estimate evapotranspiration, determine the crop coefficient of bell pepper under greenhouse conditions, calculate the virtual water content of the crop, and ultimately evaluate the virtual water content of this product. In this study, baxsed on a designed experiment, a water balance method was used to calculate the daily evapotranspiration of the plant, estimate crop coefficient values, water requirements, and virtual water content of the crop, and compare this method with empirical methods for calculating reference evapotranspiration. The evapotranspiration of the plant during the growth period was estimated to be 3.53 mm/day, and for the reference plant, it was 5.85 mm/day using the water balance method. The comparison of the obtained results showed that the FAO-Penman-Monteith method for calculating reference evapotranspiration had the highest similarity to the designed experiment method. The results of this research indicated that the crop coefficient of the product in the initial, middle, and final stages was 0.13, 0.88, and 0.6, respectively. The water requirement of bell pepper during the growth period ranged from 3800 to 5500 m3/ha, with a yield of 55 ton/ha per harvest. Additionally, the average virtual water content of the product was 46 m3/ha, and the virtual water export during the years 2015 to 2023 was 39.37 million m3 for this product.