Excess Air Factor λ from Exhaust O₂

Back-calculate λ = AFR / AFR_stoich from measured exhaust-gas oxygen percentage.

CombustionEmissions

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

\lambda \approx \frac{21}{21 - O_2\%}

Symbol	Meaning	Unit
$O_2\%$	Oxygen in dry exhaust	% v/v
$λ$	Excess-air factor

Source: ISO 10396 - Stationary source emissions sampling

Back-calculate \u03bb = AFR / AFR_stoich from measured exhaust-gas oxygen percentage.