This paper introduces the design of a signal processing circuit which can be used in conjunction with additional arrangement for measuring gas mass flow rate. Measurement is based on Bernoulli’s equation for subsonic flow. Voltages representing gas static pressure, static temperature, and difference pressure generated across an orifice plate are supposed to be taken from appropriate transducers. These voltages are processed with this circuit in such a way as to produce a digital number representing the mass flow rate value. The circuit shows a good accuracy result with uncertainty of about ±0.1%.