basic

Respiratory Exchange Ratio Calculator

RER = V̇CO₂ / V̇O₂ to infer fuel substrate.

Compute the respiratory exchange ratio (RER) from the volumes of CO₂ produced and O₂ consumed during a metabolic test, and infer the dominant fuel substrate (≈ 0.7 fat, 1.0 carbohydrate).

Priya Venkatesan By Priya Venkatesan
Published Last reviewed 1 min read

Inputs

L/min
L/min

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

RER = V̇CO₂ / V̇O₂

In depth

Compute the respiratory exchange ratio (RER) from the volumes of CO₂ produced and O₂ consumed during a metabolic test, and infer the dominant fuel substrate (≈ 0.7 fat, 1.0 carbohydrate).