Attained CII

The Attained CII is the carbon intensity a ship actually achieves over a calendar year, calculated from reported fuel consumption converted to CO2 and divided by the ship’s transport work. It is benchmarked against the Required CII to produce the A-to-E rating, with the gap between the two driving whether a corrective action plan is needed. Operators reduce the attained value through slower speeds, hull and propeller maintenance, energy-saving devices, and lower-carbon fuels. The IMO is reviewing the CII framework by 1 January 2026, which may revise the metric and band thresholds.