Peak Expiratory Flow

All calculations should be independently verified prior to clinical use. These calculators are intended to supplement, not replace, clinical judgment.

Look up predicted peak expiratory flow (PEF) by height using the Polgar & Promadhat pediatric reference table. Optionally enter a measured PEF to calculate percent of predicted and determine the asthma action-plan zone.

Height in cm

For percent of predicted, also enter measured PEF:

Measured PEF (optional) L/min

Predicted PEF L/min

Predicted PEF values are taken from the Polgar & Promadhat (1971) pediatric reference table, which covers heights from 43″ (109 cm) to 67″ (170 cm). Heights outside this range are clamped to the nearest table limit; values in centimetres are converted to the nearest inch before lookup.

Asthma action-plan zones based on percent of personal best or predicted:

Green Zone

≥ 80% of predicted
Asthma well controlled

Yellow Zone

50 – 79% of predicted
Caution — act now

Red Zone

< 50% of predicted
Medical alert

Full reference table (Polgar & Promadhat 1971):

Height (in)	Height (cm)	Predicted PEF (L/min)

References

Polgar G, Promadhat V. Pulmonary Function Testing in Children: Techniques and Standards. Philadelphia: W.B. Saunders Company; 1971.
National Heart, Lung, and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. NIH Publication No. 07-4051; 2007.