Skip to content
ENExplore Calculators

Peak Expiratory Flow Predicted Calculator

Work out peak expiratory flow predicted instantly with clear inputs, formula shown and shareable results.

About Peak Expiratory Flow Predicted Calculator

Applies the Nunn and Gregg regression equations for adult peak expiratory flow and shows the 80% and 50% action thresholds used in asthma plans.

Formula

Nunn and Gregg (1989)

Men: ln PEF = 0.544 ln(age) - 0.0151 age - 74.7/height(cm) + 5.48. Women: ln PEF = 0.376 ln(age) - 0.0120 age - 58.8/height(cm) + 5.63

Worked example

With the default values below, Peak Expiratory Flow Predicted Calculator returns Predicted peak expiratory flow of 636. Change any input above and every figure here is recalculated in your browser.

Inputs used

Sexone of Male, Female
Male
Ageaccepts 15–90 years
40 years
Heightaccepts 120–210 cm
175 cm

Results

Predicted peak expiratory flow
636 L/min
80% of predicted
509 L/min
50% of predicted
318 L/min

Step by step

  1. 1Values used
  2. 2Nunn and Gregg (1989)
  3. 3Predicted peak expiratory flow= 636 L/min
  4. 480% of predicted= 509 L/min
  5. 550% of predicted= 318 L/min

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why are 80% and 50% shown?

Personal-best asthma action plans commonly use 80% and 50% of predicted or best flow as the amber and red zones.

Does this apply to children?

No. Paediatric prediction uses height-based equations rather than the adult regression.

Related Calculators

Peak Expiratory Flow Predicted Calculator | Calcrivo