Air-Fuel Ratio (AFR) Calculator

Find the air-to-fuel mass ratio.

Air mass

Fuel mass

Air-fuel ratio (:1) 14.7

Formula: AFR = air mass ÷ fuel mass

Step-by-step with your numbers:

1. Values used:

2. Air mass = 147

3. Fuel mass = 10

5. Air-fuel ratio = Air mass / Fuel mass = 147 / 10 = 14.7:1

Did we solve your problem today?

AFR is the mass ratio of air to fuel in combustion.

The math behind it

AFR = air mass ÷ fuel mass. The stoichiometric AFR for gasoline is about 14.7:1.

147 g air / 10 g fuel → 14.7:1.

Rich vs lean?

Below stoichiometric is 'rich' (more fuel); above is 'lean'.