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About this tool
Calculate oxygen requirements including flow rates, FiO2, and delivery device selection based on patient parameters and SpO2 targets.
The Oxygen Requirement Calculator classifies a patient's SpO2 into normal, mild, moderate, severe or critical hypoxemia, estimates the FiO2 delivered by a chosen device at a given flow rate using the roughly 4% per litre per minute rule, and compares five delivery devices side by side. It applies target saturations of 94–98% for most adults and children and 88–92% where a COPD-style controlled-oxygen target applies. It is an educational reference for students and clinicians revising oxygen delivery — every real prescribing decision belongs to the treating clinician.
Open Oxygen Requirement Calculator on AltFTool — it loads instantly in your browser.
Enter Current SpO2 (%) and pick an Age Group — Adult, Child (1-12 yrs), Infant, Neonate or COPD / Chronic Lung Disease; Weight (kg) is optional.
Choose a Device Type and Flow Rate (L/min) — picking Venturi also shows the colour-coded adapter table — then press Calculate.
Read the hypoxemia level, All Devices Comparison and Recommendations, then press Copy Report or Download for an Oxygen_Report_94SpO2_*.txt file.
Five delivery devices are shown together with each one's flow range and resulting FiO2, so the trade-off between comfort and oxygen concentration is visible at once.
Neonate, infant, child, adult and COPD each carry their own target saturation band, and the guidance text calls out the COPD controlled-oxygen case specifically, rather than applying one universal target to everyone.
The report lists parameters, classification, device, flow, estimated FiO2 and the device comparison as plain text you can copy or download for teaching notes.
Roughly 24% to 44%, working from a 1–6 L/min flow range with each additional litre per minute adding about 4% FiO2. These are estimates: actual delivered FiO2 varies with the patient's respiratory rate and tidal volume, which is why cannulae are called low-flow devices.
This tool treats 96% and above as normal, 94–95% as mild, 90–93% as moderate, 85–89% as severe and below 85% as critical hypoxemia. Most adults are targeted to 94–98%, while patients at risk of CO2 retention are commonly targeted to 88–92%.
Because over-oxygenation in patients at risk of hypercapnia can worsen CO2 retention, guidance commonly sets a controlled target of 88–92% rather than 94–98%. A Venturi mask is preferred in that situation because it delivers a fixed, known FiO2 regardless of the patient's breathing pattern, and an arterial blood gas is typically checked after 30–60 minutes.
Below about 5 L/min there is not enough fresh gas flow to flush exhaled air out of the mask, so the patient rebreathes their own CO2. That is why a simple mask runs 5–10 L/min, while a non-rebreather with its reservoir bag and one-way valves runs 10–15 L/min to keep the bag inflated.
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