Carbon Intensity
Indicator (CII)
Powered by CyberSmart Smart Compliance. The IMO's Carbon Intensity Indicator (CII) regulation requires ships of 5,000 GT and above to measure and report their annual carbon intensity, receiving a rating from A to E. Smart Compliance provides regulatory obligation tracking across CII and other frameworks. With reduction factors tightening each year—reaching 11% in 2026 and 21.5% by 2030—maintaining a good rating demands continuous operational improvement and strategic planning.
What is CII?
The Carbon Intensity Indicator measures a ship's operational carbon efficiency by dividing its annual CO2 emissions by the transport work performed (capacity × distance). The attained CII is then compared against a required CII—calculated using ship type-specific reference lines and annual reduction factors—to assign a rating from A to E.
The regulation is part of the IMO's short-term GHG reduction measures under MARPOL Annex VI, aligned with the 2023 IMO GHG Strategy target of reducing CO2 emissions per transport work by at least 40% by 2030 compared to 2008 levels. Rating boundaries tighten each year, meaning a ship rated C today could fall to D or E without continuous improvement.
CII Rating Scale
Well below the required CII. Best operational performance.
Below the required CII. Good performance with room for optimization.
Meets the required CII. Baseline compliance, improvement recommended.
Above the required CII. Corrective action plan required if rated D for 3 consecutive years.
Significantly above the required CII. Corrective action plan required immediately.
D/E rated ships must implement corrective action plans. Continued poor ratings may affect port state control inspections and charter opportunities.
Reduction Factors (vs 2019 Baseline)
Reduction factors set by MEPC.400(83). Factors for 2027-2030 are stricter than original projections, reaching 21.5% by 2030 to align with IMO's 40% transport work reduction target.
Compliance Requirements
CII compliance involves annual calculation, rating assignment, SEEMP maintenance, and—for underperforming vessels—mandatory corrective action planning.
Annual Calculation
CII is calculated by dividing annual CO2 emissions by the product of vessel capacity (DWT or GT) and distance sailed. The attained CII is compared against the required CII for the ship type and size.
Rating Assignment
Ships receive an annual rating from A (major superior) to E (inferior) based on how their attained CII compares to the required CII. Rating boundaries are updated annually with tightening reduction factors.
SEEMP Part III
All ships must maintain a Ship Energy Efficiency Management Plan (SEEMP Part III) with a 3-year implementation plan, required CII values, and planned corrective actions. Must be updated by Dec 31, 2025 for the 2026-2028 period.
Corrective Actions
Ships rated D for three consecutive years or E for any single year must submit a corrective action plan demonstrating how they will achieve at least a C rating. Plans are reviewed by the Administration.
Our CII Solutions
From initial CII assessment through to continuous improvement, we provide comprehensive support to help your fleet achieve and maintain strong ratings.
CII Rating Calculations (Smart Compliance)
Accurate CII calculations using verified fuel consumption and voyage data to determine your current rating and trajectory, tracked through Smart Compliance.
- Annual attained CII calculation
- Rating determination against boundaries
- Multi-year performance trend analysis
- Ship type-specific benchmarking
SEEMP Part III Development
Comprehensive SEEMP Part III creation meeting all IMO requirements, including the enhanced 2026-2028 implementation plan.
- Full SEEMP Part III drafting
- 3-year implementation planning
- Required CII target setting
- Self-evaluation & improvement schemes
Energy Efficiency Optimization
Technical and operational measures to improve your vessel CII rating, from quick wins to long-term fleet strategies.
- Hull & propeller optimization
- Speed & power management
- Weather routing integration
- Alternative fuel assessment
Corrective Action Plans
For D or E rated vessels, we develop actionable corrective plans that satisfy Administration requirements and deliver measurable improvements.
- Root cause analysis of poor ratings
- Action plan development & review
- Implementation support & monitoring
- Effectiveness assessment & reporting
Data Management & Verification
Robust data collection systems and verification support to ensure accurate CII calculations and avoid rating disputes.
- Fuel consumption data systems
- Voyage data quality assurance
- Third-party verification liaison
- IMO DCS data integration
Continuous Improvement (Smart Compliance)
Ongoing performance monitoring and advisory support via Smart Compliance to maintain or improve CII ratings as reduction factors tighten annually.
- Monthly performance dashboards
- Reduction factor impact analysis
- Best practice implementation
- Regulatory update briefings
Improvement Strategies
Improving your CII rating requires a combination of technical modifications, operational changes, and strategic fuel choices. Here are the most effective approaches.
Engine & Hull Optimization
Regular engine tuning, propeller polishing, hull cleaning, and waste heat recovery systems can reduce fuel consumption by 5-15%. These are often the most cost-effective first steps for CII improvement.
Voyage & Speed Optimization
Weather routing, just-in-time arrivals, optimal trim management, and speed reduction programs. Even modest speed reductions yield significant fuel savings due to the cubic relationship between speed and power.
Alternative Fuels & Technologies
Transitioning to LNG, methanol, or biofuel blends can substantially lower CO2 per transport work. Wind-assisted propulsion and air lubrication systems offer additional fuel savings of 5-30%.
Frequently Asked Questions
Common questions about our CII Rating services and compliance requirements.
The Carbon Intensity Indicator (CII) is an IMO requirement under MARPOL Annex VI that rates ships from A (Major Superior) to E (Inferior) based on their operational carbon intensity. Ships of 5,000 GT and above on international voyages must calculate their CII annually, with reduction targets tightening each year.
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Services that complement CII Rating for comprehensive maritime compliance.
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FuelEU Maritime GHG intensity compliance including pooling arrangements, RFNBO planning, and shore power readiness.
Learn moreReady to Optimize Your CII?
With reduction factors tightening annually and SEEMP Part III updates required by end of 2025, now is the time to assess your fleet's performance and develop a clear improvement roadmap.