A peak flow meter is described with a body having a sample channel and at least onebypass channel. One of at least two flow range scales may be selected using a flowrange selector to adjust the sensitivity of the peak flow meter. A flow range selectionindicator provides visual reference as to which flow range scale has been selected.A peak flow calculator used in cooperation with zone indicators on the peak flowmeter permits a user to customize the peak flow meter for that user's predictedpersonal best exhalation range.
