Systems and methods described herein concern estimating the mass of a vehicle. One embodiment uses a slope estimator to estimate the grade of a roadway on which the vehicle is traveling; inputs state estimates from the slope estimator, an estimated wheel force, and an estimated wheel acceleration to a secondary mass estimator that calculates a first estimated mass of the vehicle; selects, based at least in part on the first estimated mass, a calibration value using a tuning map; inputs the calibration value, the estimated wheel force, the state estimates, and a measurement noise value to a main mass estimator that calculates a second estimated mass of the vehicle that is more accurate than the first estimated mass due, at least in part, to the calibration value; and adjusts automatically one or more operational parameters of the vehicle based, at least in part, on the second estimated mass.