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PaO2 FiO2 Ratio Calculator

Work out pao2 fio2 ratio instantly with clear inputs, formula shown and shareable results.

About PaO2 FiO2 Ratio Calculator

Divides arterial oxygen tension by the inspired oxygen fraction and maps the result onto the Berlin ARDS severity bands.

Formula

P/F ratio

P/F = PaO2 (mmHg) / FiO2 (as a fraction). Berlin bands: mild 201-300, moderate 101-200, severe <=100 with PEEP >=5 cmH2O

Worked example

With the default values below, PaO2 FiO2 Ratio Calculator returns PaO2/FiO2 ratio of 200. Change any input above and every figure here is recalculated in your browser.

Inputs used

PaO2accepts 20–600 mmHg
80 mmHg
Inspired oxygen fractionaccepts 21–100 %
40 %

Results

PaO2/FiO2 ratio
200 mmHg
Berlin severity band
Moderate ARDS range (101-200)
Ratio in kPa
26.7 kPa

Step by step

  1. 1Values used
  2. 2P/F ratio
  3. 3PaO2/FiO2 ratio= 200 mmHg
  4. 4Berlin severity band= Moderate ARDS range (101-200)
  5. 5Ratio in kPa= 26.7 kPa

Assumptions and limits

  • The result is derived only from the 2 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 1 decimal place, 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

Does PEEP matter?

Yes. The Berlin definition requires at least 5 cmH2O of PEEP or CPAP for the bands to apply.

How do kPa units compare?

Divide the mmHg ratio by 7.5; a P/F of 300 mmHg is 40 kPa.

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PaO2 FiO2 Ratio Calculator – Calculate PaO2/FiO2 ratio