AFR to Lambda Calculator
FUEL CONVERSION
Air/Fuel Ratio ↔ Lambda
Select a brand, then select the fuel you run to build its conversion table. The calculation uses that fuel's published stoichiometric A/F ratio.
Check your wideband's display scale. Actual fuel AFR uses the selected fuel's stoichiometric ratio. A wideband set to a fixed 14.7 gasoline scale displays lambda × 14.7, even when running another fuel. Select the scale matching the number you enter below.
Lambda = actual AFR ÷ fuel stoichiometric AFR. Actual AFR = lambda × fuel stoichiometric AFR. Lambda 1.00 is stoichiometric; below 1.00 is rich and above 1.00 is lean.
| Lambda | Actual fuel AFR | 14.7-scale display AFR |
|---|
All AFR values are mass ratios, shown as :1. This table converts units; the values shown are not recommended tuning targets. Missing published values require a custom manufacturer-specified ratio. Ethanol blends can vary; use the ratio for your actual blend.