Air to Fuel Ratio (AFR) Calculator

Formula

To calculate the Air to Fuel Ratio (\(AFR\)):

\[ AFR = \frac{Mair}{Mfuel} \]

Where:

\(AFR\) is the air to fuel ratio
\(Mair\) is the mass of the air
\(Mfuel\) is the mass of the fuel

What is an Air to Fuel Ratio?

Air to fuel ratio is a measure of the total mass of the air per unit of mass of fuel used for an engine. Sometimes the air to fuel ratio can be calculated volumetrically, but this is uncommon.

Common Air to Fuel Ratios of Fossil Fuels

Methanol: 6.47:1
Diesel: 14.5:1
Propane: 15.67:1
Gasoline: 14.7:1
Hydrogen: 34.3:1
Methane: 17.19:1

Example Calculation 1

Let's assume the following values:

Mass of Air (\(Mair\)) = 14.7 kg
Mass of Fuel (\(Mfuel\)) = 1 kg

Using the formula:

\[ AFR = \frac{14.7}{1} = 14.7 \]

The air to fuel ratio is 14.7:1.

Example Calculation 2

Let's assume the following values:

Mass of Air (\(Mair\)) = 34.3 kg
Mass of Fuel (\(Mfuel\)) = 1 kg

Using the formula:

\[ AFR = \frac{34.3}{1} = 34.3 \]

The air to fuel ratio is 34.3:1.