Maritime & Ship Management

CII

Carbon Intensity Indicator

The Carbon Intensity Indicator (CII) is the IMO's mandatory operational rating of a ship's carbon efficiency, effective from January 2023. Each ship 5,000 GT and above receives an annual rating from A (major superior) to E (inferior) based on actual CO2 emissions per cargo capacity per nautical mile sailed.

Vessels rated D for three consecutive years, or E for one year, must develop a Corrective Action Plan to bring CII back to C or better. CII is becoming a major commercial factor: charterers increasingly prefer A/B-rated tonnage; lenders may impose CII covenants; insurers may price by rating.

Why it matters

CII has turned carbon efficiency into a commercial fact. Charterers increasingly prefer A/B-rated tonnage, lenders write CII covenants into ship finance, and insurers may price by rating — so a slipping CII can strand a ship commercially even when it is perfectly seaworthy.

Diagram
A
Major superior
B
Minor superior
C
Moderate
D
Minor inferior
E
Inferior
Each ship gets an annual A–E rating; D for three years running, or E once, forces a corrective action plan.
Formula
CII (AER) = Total CO₂ emitted ÷ (Deadweight × Distance sailed)
CO₂ — total emissions over the year, derived from fuel consumed
DWT × Distance — the transport work done — capacity times nautical miles
The attained CII is compared against an annually tightening required value to set the A–E rating.
Also known as
IMO CII
Related terms
MARPOL SOLAS IMO Classification Society
Where this matters at WHIZTEC
Ship Management Software
More Maritime & Ship Management terms

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