Work out oxygen flow rate instantly with clear inputs, formula shown and shareable results.
Works backwards from a target inspired oxygen concentration to the flow needed, using the rule of thumb that each litre per minute of nasal oxygen adds about 4%.
Flow from target FiO2
Flow (L/min) = (target FiO2% - 21) / increment per L/min, with the increment about 4% for nasal cannulae
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
It is only a guide; actual inspired oxygen varies with tidal volume, respiratory rate and mouth breathing.
When a precise concentration matters, such as in type 2 respiratory failure, a Venturi mask should be used instead.