Bosch Smoke Number Interpretation

Quick classification of a Bosch smoke-number reading from 0 (clean) to 10 (black), aligned with typical Tier II/III engine limits.

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

\text{FSN = 10 - (Reflectance \% / 10)}

Symbol	Meaning	Unit
$FSN / BSN$	Bosch / Filter Smoke Number

Source: ISO 10054 - Measurement of smoke value from compression-ignition engines

Quick classification of a Bosch smoke-number reading from 0 (clean) to 10 (black), aligned with typical Tier II/III engine limits.