Predicted Peak Expiratory Flow (PEF)

Calculates predicted peak expiratory flow based on age, height, and sex using NHANES III reference equations (Hankinson 1999). Used to assess asthma severity and monitor response to treatment.

years
Age in years.
cm
Standing height in centimeters.
Sex at birth.
NHANES III equations include race/ethnicity adjustments.

Enter age, height, and sex to calculate predicted PEF

References

  1. Spirometric reference values from a sample of the general U.S. population — American Journal of Respiratory and Critical Care Medicine (1999)
  2. NHANES III Spirometry Reference Equations — CDC/NCHS (1996)

Clinical Notes & Warnings

  • PEF is effort-dependent and requires proper technique.
  • Reference equations vary by population; NHANES III is standard for North America.
  • Race/ethnicity corrections are approximate and may not apply to all individuals.
  • PEF variability >20% suggests asthma.
  • PEF is less sensitive than FEV1 for detecting early airflow limitation.

The NHANES III reference equations are the most widely used in North America. Linear approximations are commonly used for quick calculation: Male PEF (L/min) = [3.72 x height(cm)] - [2.49 x age(years)] + 303.42; Female PEF (L/min) = [2.60 x height(cm)] - [1.93 x age(years)] + 216.43. Lower limit of normal (LLN) is approximately 80% of predicted.