The present invention is directed to a spirometer comprising a piezoelectric sensor and the use of the spirometer in measuring a users lung performance and/or tracking a users lung performance over a period of time. The spirometer is configured so that fluid flow through a housing produces oscillating stresses in a piezoelectric material. The oscillating stresses produce an electric signal. Characteristics of the electric signal, such as the magnitude of the signal at particular frequencies, can be measured and used to determine the rate of fluid flow through the housing during inhalation or exhalation. The fluid flow characteristics may then be displayed on a variety of devices, such as a smartphone, a personal computer, etc.