A method of predicting multiphase critical flow through restrictions is proposed. Hitherto, constant pressure ratios are assumed for critical flow conditions to be operational. This new method is dependent on the composition of the flowing fluid and the operating conditions of temperature and pressure. The method is simple and employs dynamic conditions and is independent on the type of flow, the continuous phase and the position of restriction in the flow system. The procedure for the use of this method is outlined. An example illustrates its applicability in multiphase flow metering and evaluation of pressure drop across bit nozzles in foam and aerated drilling fluids.