Arterial Oxygen Content Calculator

Calculator

Hemoglobin

Enter the measured hemoglobin concentration.

Hemoglobin unit

The calculator converts all values to g/dL.

Arterial oxygen saturation (SaO₂)

Use a measured saturation value when possible.

SaO₂ unit

Percent values are divided by 100 internally.

Arterial oxygen pressure (PaO₂)

Commonly obtained from arterial blood gas testing.

PaO₂ unit

kPa values are converted to mmHg for calculation.

Cardiac output (optional)

Needed only for estimated oxygen delivery.

Cardiac output unit

Oxygen delivery uses liters per minute.

Hemoglobin oxygen-binding constant

Default clinical estimate: 1.34 mL O₂ per gram Hb.

Oxygen solubility coefficient

Default clinical estimate: 0.0031 mL O₂/dL/mmHg.

Formula used

Arterial oxygen content (CaO₂) = (1.34 × Hemoglobin × SaO₂) + (0.0031 × PaO₂)

1.34 × Hemoglobin × SaO₂ estimates oxygen bound to hemoglobin.
0.0031 × PaO₂ estimates oxygen dissolved in plasma.
CaO₂ is reported here in mL O₂ per dL of blood.
Estimated oxygen delivery (DO₂) = CaO₂ × Cardiac Output × 10.

The bound oxygen term usually dominates total content, while the dissolved term contributes a much smaller amount under most clinical conditions.

How to use this calculator

Enter hemoglobin in g/dL or g/L.
Enter arterial oxygen saturation as a percent or fraction.
Enter PaO₂ in mmHg or kPa.
Optionally enter cardiac output to estimate oxygen delivery.
Keep the default constants unless your protocol uses different values.
Click the calculate button to display the result above the form.
Use the export buttons to save the result as CSV or PDF.

Example data table

Scenario	Hemoglobin	SaO₂	PaO₂	Cardiac Output	CaO₂	Estimated DO₂
Typical adult example	15.0 g/dL	97%	95 mmHg	5.0 L/min	19.79 mL/dL	989.6 mL/min
Lower hemoglobin example	10.0 g/dL	96%	90 mmHg	5.0 L/min	13.15 mL/dL	657.9 mL/min
Reduced saturation example	14.0 g/dL	88%	60 mmHg	4.8 L/min	16.68 mL/dL	800.8 mL/min

FAQs

1. What does arterial oxygen content measure?

It estimates how much oxygen is carried in arterial blood. The value combines oxygen attached to hemoglobin with the smaller amount dissolved directly in plasma.

2. Why is hemoglobin so important in this calculation?

Most oxygen in blood is bound to hemoglobin. Because of that, a patient can have a normal PaO₂ yet still have reduced oxygen content if hemoglobin is low.

3. Why does dissolved oxygen contribute less?

Only a small amount of oxygen dissolves in plasma at normal pressures. The dissolved component rises with higher PaO₂, but it usually remains much smaller than hemoglobin-bound oxygen.

4. Can I use SpO₂ instead of SaO₂?

You can use SpO₂ as an estimate when direct arterial saturation is unavailable, but measured SaO₂ from blood gas analysis is usually better for clinical precision.

5. What unit is used for the result?

The main output is mL O₂ per dL of blood. The calculator also shows the same result per liter to support comparisons across reports.

6. What is a common normal range for CaO₂?

Many adults fall roughly around 16 to 22 mL O₂/dL, but the exact value depends on hemoglobin concentration, oxygen saturation, pressure, altitude, and clinical setting.

7. Why does the calculator offer custom constants?

Some educational sources, devices, or institutional protocols use slightly different oxygen-binding or solubility constants. Editable constants help align the estimate with your preferred method.

8. Does this tool replace medical judgement?

No. It is an educational calculator. Diagnosis and treatment decisions should always consider symptoms, examination, blood gases, hemoglobin status, perfusion, and clinician assessment.