AbstractTo facilitate agricultural water rights trading reform in China and improve the efficiency of agricultural irrigation, an effective and practical approach called the conversion coefficient from electricity consumption to irrigation water supply (CCECIWS) method is introduced in this study. Application of this method in Siyang County is meticulously investigated. First, four measurement strategies are employed for the precise estimation of the volume of irrigation water from agricultural irrigation water pumps (AIWPs) in Siyang County. Then, the CCECIWS data collected through on‐site testing and the distribution pattern of the CCECIWSs of AIWPs are analysed, and the ranges of the CCECIWS values for different groups are delineated. Conjoint analysis is conducted to quantify the influence of two factors on the CCECIWSs. Finally, three regression models are developed and validated to predict the CCECIWSs for the remaining 60% of the total AIWPs, which are not tested on site. The prediction results show that the regression models have acceptable accuracy. The contribution of this research is the provision of a practical and efficient CCECIWS method to indirectly evaluate the irrigation water supply, saving both time and economic costs and laying the foundation for future research on this topic.