A well advisor system and console for fluid gains and losses during well drilling and well construction activities. The system may be accessed through one or more workstations, or other computing devices, which may be located at a well site or remotely. The system is in communication with and receives input from various sensors. It collects real-time sensor data sampled during operations at the well site. The system processes the data, and provides nearly instantaneous numerical and visual feedback through a variety of graphical user interfaces (“GUIs”), which are presented in the form of an operation-specific console.