P/F Ratio Calculator
Calculate the PaO₂/FiO₂ ratio and interpret oxygenation severity. Use FiO₂ as a decimal or percentage and the calculator will normalize it for you.
Calculator
Calculate P/F Ratio
Formula: P/F Ratio = PaO₂ ÷ FiO₂. Enter FiO₂ as 0.40 or 40.
P/F Ratio
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Enter PaO₂ and FiO₂ to calculate the ratio.
Formula
P/F Ratio Formula
P/F Ratio = PaO₂ ÷ FiO₂
Example: PaO₂ 80 on FiO₂ 0.40 → 80 ÷ 0.40 = 200
Example: PaO₂ 80 on FiO₂ 0.40 → 80 ÷ 0.40 = 200
| P/F Ratio | Interpretation |
|---|---|
| > 300 | Better oxygenation |
| 201–300 | Mild oxygenation impairment range |
| 101–200 | Moderate oxygenation impairment range |
| ≤ 100 | Severe oxygenation impairment range |
Continue Learning
Connect this result to clinical reasoning
Review the full P/F ratio guide or practice ABG interpretation with patient cases.