A system for calculating and reporting slump in a delivery vehicle having a mixing drum (14) and hydraulic drive (16) for rotating the mixing drum, including a rotational sensor (20) configured to sense a rotational speed of the mixing drum, a hydraulic sensor (22) coupled to the hydraulic drive and configured to sense a hydraulic pressure required to turn the mixing drum, and a communications port (26) configured to communicate a slump calculation to a status system (28) commonly used in the concrete industry, wherein the sensing of the rotational speed of the mixing drum is used to qualify a calculation of current slump based on the hydraulic pressure required to turn the mixing drum.