Abstract: An apparatus and method for automatically determining the measurement accuracy of an uncalibrated field fluid flow meter by comparing its fluid flow volume, measurement, V.sub.f, to a fluid flow volume measurement, V.sub.m, of a master meter of known accuracy. The apparatus comprises fluid flow device operably coupled to the field and master meters for passing a common fluid stream through each of the meters at a predetermined flow rate until a predetermined volume of fluid has been registered by the field meter; a first measurement signalling device for a generating data representing the fluid volume registered by each of the meters; a second signalling device for generating data representing input temperatures and pressures to each of the meters; and a computer coupled to the fluid flow device for automatically controlling the flow rate and calculating the accuracy of the field meter.