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IMO CII Rating Calculator

Calculate your vessel's Carbon Intensity Indicator rating (A–E) for 2026–2028. Instant result based on MEPC.354(78) reference lines and annual reduction factors.

MEPC.354(78)
MEPC.338(76)
MARPOL Annex VI Reg. 28

Enter vessel + voyage data

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Ship Type
Year
DWT (tonnes)
Annual Distance (nm)
Fuel Type
Fuel Mass (tonnes)
Your rating
–
Enter values to see rating
A
B
C
D
E
Attained CII–
Required CII–
CO₂ emitted–

Track CII per voyage, project year-end rating, flag D/E-trajectory vessels — automatically across your fleet.

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Fuel emission factors

Cf values from MARPOL Annex VI Regulation 26 Appendix IX — same as IMO DCS and EEDI.

HFO
3.114
tCO₂/tFuel
VLSFO
3.150
tCO₂/tFuel
MGO / MDO
3.206
tCO₂/tFuel
LNG
2.750
tCO₂/tFuel
LPG (propane)
3.000
tCO₂/tFuel
Methanol
1.375
tCO₂/tFuel
Ammonia (TtW)
0.000
tCO₂/tFuel

Rating band boundaries

Ratio (Attained/Required) is compared to ship-type-specific boundaries. C is the required minimum.

Ship Typed1 (A/B)d2 (B/C)d3 (C/D)d4 (D/E)
Bulk carrier0.860.941.061.18
Tanker0.820.931.081.28
Container ship0.830.941.071.19
LNG carrier0.890.981.061.13
General cargo0.830.941.061.19

Frequently asked questions

What is IMO CII rating?
IMO Carbon Intensity Indicator (CII) rates ships A (best) to E (worst) based on CO₂ emitted per tonne-mile. Ships rated D for 3 consecutive years or E for 1 year must file a corrective action plan under MARPOL Annex VI Regulation 28.
How is CII calculated?
CII_attained = (Fuel × Emission Factor) / (DWT × Distance_nm). Compared to a ship-type-specific reference line from MEPC.338(76) adjusted by a year-reduction factor from MEPC.354(78). Ratio determines the A-E band. See our CII methodology guide.
What are the CII reduction factors 2026-2028?
MEPC.354(78) sets annual reduction: 2026 = 11%, 2027 = 13%, 2028 = 15%. Required CII = reference line × (1 − reduction factor).