The Potential Climatic Water Productivity(PCWP) is an important indicator to quantify the effect of intrinsic factors on physical water productivity. The crop calendar is one of the important factors affecting this index. Considering the importance of maize farming and the necessity of improving water productivity, PCWP index was investigated for eight agronomic calendars and five maize farms in the 2015 -16. Crop calendars were extracted from available official sources and expert meetings. The PCWP components were determined from the FAO Growth Model(yield) and the standard FAO Penman-Monteith method(evapotranspiration). The mean PCWP for maize forage in the second crop cultivation increased by 23 percent as compared to the first cultivation, therefore, the use of second cultivation calendars is recommended in regard to the promoting water productivity. In spite of a 13.7 percent increase in PCWP in the second maize-grain cultivation, the use of the first cultivation calendars is recommended. Due to changes in water productivity(WP) and its components, water allocation and irrigation scheduling based on ETc appropriate to the crop calendar is essential. However, WP based ETc and actual yield are not appropriate for correct comparison, analysis and crop calendar selection, so it is necessary to use PCWP values based on climatic potential production (CPP) under water conditions (IPP) and ETc .