A method for determining lubricant consumption by a transmission mechanism disposed on a machine tool includes steps of: a) estimating, based on an operational speed and a predetermined first predictive model, a total operational physical quantity; b) estimating, based on an individual operational physical quantity and the total operational physical quantity, a total operational count; c) receiving actuation information from the machine tool, and calculating a partial operational count based on the actuation information; and d) calculating, based on the partial operational count and the total operational count, a ratio between an amount of lubricant consumption within a time period and a total amount of lubricant.