Respiratory Quotient [STP Volume]

The Respiratory Quotient calculator compute the respiratory quotient based on the amount of CO₂ exhaled and O₂ inhaled.

INSTRUCTIONS: Choose units and enter the following:

• (CO₂) This is the amount of CO₂ expelled
• (O₂) This is the amount of O₂ taken in.

Respiratory Quotient (RQ): The calculator returns the quotient.

The Math / Science

The formula for the Respiratory Quotient is:

    RQ = CO₂/O₂

where:

• RQ is the respiratory quotient
• CO_{2 i}s the volume of CO₂ exhaled
• O₂ is the volume of O2 inhaled.

The Respiratory Quotient or Respiratory Coefficient, RQ, is a ratio of the carbon dioxide expelled from the body to the amount of oxygen taken in.  This version of the RQ is defined in terms of volumes of `"CO"_2` and `O_2` assuming both volumes are defined at Standard Temperature and Pressure (STP).

RQ is unit-less number often used to compute basal metabolic rate (BMR).  The RQ is estimated from carbon dioxide production and can be considered a form of indirect calorimetry.

RQ values typically range from 1.0 (representing pure carbohydrate oxidation, expelling equivalent amounts of `"CO"_2` to the oxygen intake)  to 0.7 seen in pure fat oxidation.  The `O_2` in and the `"CO_2` out can be measured with a respirometer, which can then measure the RQ of a person (or individual organism) taking into account health and activity level and other factors contributing to the ratio's value.