Peak Flow Monitoring Calculator

Personal best percentage and zone classification.

Current PEF (L/min)

Personal Best PEF (L/min)

Age (years)

Height (cm)

Sex (0=Male, 1=Female)

Tab to move between fields

% of Personal Best

80%

Zone (0=Green, 1=Yellow, 2=Red)0

% of Predicted63.5%

Predicted PEF (L/min)630

Green Zone Threshold (L/min)400

Yellow Zone Threshold (L/min)250

PEF Variability (%)20%

How to Use This Calculator

Enter your current PEF (L/min) and personal best PEF (L/min).
Enter age (years), height (cm), and sex to calculate the predicted normal PEF for comparison.
Review your percent of personal best and percent of predicted PEF.
Check your asthma zone (green >=80%, yellow 50-79%, red <50%) and recommended action.
Record daily readings at the same time each day for meaningful trend monitoring.

How the result changes with Personal Best PEF (L/min)

Current PEF (L/min): Today's measured peak expiratory flow in liters per minute.
Personal Best PEF (L/min): Highest PEF achieved when well-controlled (over 2 weeks of good control).
Age (years): Patient age in years.
Height (cm): Patient height in centimeters.
Sex (0=Male, 1=Female): Biological sex for predicted PEF calculation.

% of Personal Best: Current PEF as percentage of personal best. ≥80% = Green, 50-79% = Yellow, <50% = Red.
Zone (0=Green, 1=Yellow, 2=Red): Traffic light zone: 0 = Green (well controlled), 1 = Yellow (caution), 2 = Red (emergency).
% of Predicted: Current PEF as percentage of age/sex/height-predicted value.
Predicted PEF (L/min): Expected PEF for a healthy person of same age, sex, and height.
Green Zone Threshold (L/min): PEF values above this (80% of personal best) indicate good control.
Yellow Zone Threshold (L/min): PEF values above this (50% of personal best) but below green indicate caution.
PEF Variability (%): Percentage drop from personal best. >20% variability suggests poorly controlled asthma.

Identify Input Parameters
4 parameters
Current PEF (L/min) = 400, Personal Best PEF (L/min) = 500, Age (years) = 35, Height (cm) = 170 = 5 input(s) provided
Calculate % of Personal Best
% of Personal Best = (currentPEF / personalBest) * 100
80 = 80
Calculate Zone
0 = 0
Calculate % of Predicted
% of Predicted = (currentPEF / predictedPEF) * 100
63.5 = 63.5