Oxygen Consumption (VO₂) Calculator

Oxygen consumption is the rate at which the body uses oxygen, calculated from how much oxygen content drops between arterial and venous blood, multiplied by how much blood the heart pumps.

Calculate Oxygen Consumption

L/min
Normal ~4–8 L/min.
Enter a value between 1 and 15.
mL/dL
Normal ~16–20 mL/dL.
Enter a value between 5 and 25.
mL/dL
Normal ~14–15 mL/dL.
Enter a value between 2 and 24.
VO₂
250
mL O₂/min
Normal range
CaO₂ − CvO₂
5.0 mL/dL
Cardiac output
5 L/min

How It's Calculated

Fick principle
VO₂ = Cardiac Output × (CaO₂ − CvO₂) × 10

What the Result Means

≥ 180

Normal resting range (~200–250 mL/min) and above.

120–180

Mildly low — reduced delivery or extraction.

60–120

Low consumption.

< 60

Very low — check inputs and clinical context.

Worked Example

Given: cardiac output 5 L/min, CaO₂ 20, CvO₂ 15 mL/dL.

  1. Difference = 20 − 15 = 5 mL/dL
  2. VO₂ = 5 × 5 × 10 = 250 mL/min (normal).

The Fick Principle

The oxygen the tissues extract, scaled by blood flow, is what the body consumes.

CaO₂ CvO₂ extraction used × cardiac output × 10 = VO₂

Frequently Asked Questions

Why multiply by 10?

It's a unit conversion. Cardiac output is in L/min and oxygen content is in mL/dL, so multiplying by 10 aligns the units and gives VO₂ in mL/min.

What is a normal VO₂?

About 200–250 mL/min at rest, roughly 3–4 mL/kg/min. It rises sharply with exercise, fever, and other high-demand states.

What is the Fick principle?

It states that oxygen consumption equals blood flow multiplied by the amount of oxygen each unit of blood gives up — cardiac output times the arterial-venous content difference.

Can VO₂ be used to calculate cardiac output?

Yes — rearranging the Fick equation lets you solve for cardiac output if VO₂ is measured directly, which is the basis of the Fick cardiac-output method.

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