Abstract: Pocket-size medical spirometer comprising a housing and a measurement unit (MU), for measuring rate of total flow when a user exhales through the spirometer. The MU comprises a fluidic jet oscillator adapted to generate oscillating flow with frequency dependent on the rate of flow therethrough. The MU is disposed within the housing so as to form a bypass flow path defined between an outer surface of the MU and an inner surface of the housing. A measurement flow path is defined through the fluidic jet oscillator, such that the total flow is divided into a bypass flow and a measurement flow, the latter being less than the former at least by an order of magnitude. The spirometer further comprises a pressure or velocity transducer and an electronic circuit adapted to derive the total flow rate or volume from the transducer signal.