Method and system for calibrating a mass flow sensor. The mass flow sensor includes an impact sensor that receives an impact force due to collisions with a plurality of solid particles to generate an output signal. A model relates a mass flow input to the output signal. At least one measurable parameter is varied over a plurality of samples by varying a physical component of the mass flow sensor, and a generated output signal is received. The model can be calibrated based on the received output signal for each of the plurality of samples. A mass-flow input can also be estimated while simultaneously updating the model.