Peak Expiratory Flow (PEF) — Predicted Normal Calculator

Calculates the predicted normal peak expiratory flow (PEF) based on patient age, sex, and height using established Caucasian normative reference ranges (Wright and McKerrow 1959 / Nunn and Gregg 1989 values). Peak expiratory flow is the maximum airflow rate achieved during a forced exhalation from a position of full inspiration, measured in liters per minute (L/min). Predicted normal PEF is used as a reference to calculate the personal best or percentage of predicted PEF for asthma and COPD severity classification and monitoring. PEF < 50% predicted = severe acute exacerbation; < 25% predicted = life-threatening.