Oxygenation Calculator Calculate PaO2/FiO2 (P/F) Ratio and Oxygen Index (OI) for clinical assessment. P/F Ratio PaO2 (mmHg) FiO2 (%) Oxygen Index (OI) Mean Airway Pressure (MAP) Leave as 0 if only calculating P/F Ratio Calculate P/F Ratio -- -- Oxygen Index (OI) -- --