CII Attained - Carbon Intensity Indicator
Compute a ship's annual Attained CII per MEPC.336(76), its Required CII for the chosen year, and the resulting A–E rating per MEPC.339(76).
Ship & voyage inputs
Fuel consumption
One row per fuel type burned in the reporting year. Add as many as you need.
Formula, assumptions, and boundaries
Attained CII is computed per MEPC.336(76) as the Annual Efficiency Ratio (AER) for most ship types:
- Fⱼ - mass of fuel j burned during the reporting year (tonnes).
- Cfⱼ - fuel-to-CO₂ conversion factor for fuel j from MEPC.364(79). Embedded values are defaults; certified BDN values should be used for regulatory filings.
- Capacity - deadweight (DWT) for cargo ships; gross tonnage (GT) for ro-pax, ro-ro vehicle carriers, and cruise ships. See MEPC.337(76) for the ship-type mapping.
- Distance - total nautical miles travelled in the reporting year per IMO DCS data.
Required CII = reference line × (1 − Z), where the reference line is a × Capacity−c per MEPC.337(76) Table 1, and Z is the annual reduction factor per MEPC.338(76): 5% (2023), 7% (2024), 9% (2025), 11% (2026).
Rating boundaries d1…d4 come from MEPC.339(76). The attained value is compared against required × dₓ to yield an A–E grade. A–C are compliant ratings; D for three consecutive years or E for one year triggers a SEEMP Part III corrective action plan.
This tool uses a subset of ship types, conversion factors, and reference-line coefficients. Cross-check with the latest IMO MEPC consolidated text before submitting to a flag administration.