An apparatus for liquid flow detection especially adapted for use with an IV administration set includes an energy beam emitter device and an energy beam detector device. A drip chamber is connected in flow communication with a fluid reservoir of the IV administration set. Fluid flow is directed through a drop forming orifice into the drip chamber and thence into a supply tube for the IV administration set. The energy beam emitter device produces a pair of parallel spaced beams which are directed across the free fall path of the fluid drops and to the energy beam detector device. As the drops enter and exit the energy beams, signals are generated by the detector device as a function of time and are fed to a microprocessor. Using this data and relationships developed with conventional mathematics, the diameter of each drop can be extrapolated. From the drop diameter, the drop volume can then be calculated and used with the time measurements to provide extrapolated outputs of flow-rate and total volume. This data may be used for display or control purposes.