Two of the most important decarbonization rules in global shipping, EEXI and CII, are creating confusion across the industry. Many shipowners are unsure how the rules differ or what actions are required to stay compliant. This easy-to-follow guide explains both regulations clearly so you can understand what they mean, how they affect your operations, and what steps to take next. No jargon, just the essential facts.
Before diving into the technical details, here’s a quick overview of what EEXI and CII actually mean. These definitions will help you get a clear baseline before tackling compliance or strategy.
EEXI (Energy Efficiency Existing Ship Index)
CII (Carbon Intensity Indicator)
A technical measure that evaluates how energy efficient a ship’s design is based on its specifications. Applies to existing ships built before IMO design efficiency rules came into effect.
An operational measure that rates how carbon efficient a ship is based on its real-world emissions per cargo mile over the course of a year.
Focuses on design limitations, such as installed engine power, fuel type, and hull shape. One-time compliance check tied to a ship’s technical file.
Involves continuous annual reporting and performance ratings from A (best) to E (worst). Poor performance requires a corrective action plan.
Typically met by limiting engine power, upgrading propellers, or retrofitting energy-saving devices.
Influenced by operational decisions such as voyage speed, route planning, and cargo optimization.
Why EEXI and CII Were Created
The maritime industry contributes nearly 3 percent of global greenhouse gas emissions, and regulators are pushing hard for cleaner operations. EEXI and CII were both introduced by the IMO to help decarbonize shipping in measurable, enforceable ways. But each targets a different part of the emissions equation, design versus performance. The table below explains what motivated each rule and how they fit into the bigger picture.
Why These Rules Exist
Regulation
Core Objective
Reason for Implementation
EEXI
Improve design-based energy efficiency of older ships
Ships built before efficiency rules were unregulated. EEXI helps bring legacy fleets in line with modern standards.
CII
Track and improve real-world carbon performance
Design alone isn’t enough. CII ensures ships operate efficiently across actual voyages, routes, and cargo loads.
Both
Support IMO's 2030 and 2050 decarbonization goals
The shipping sector must reduce GHG intensity by 40% by 2030 and move toward full decarbonization by 2050.
Note: Based on IMO MARPOL Annex VI updates and 2023–2025 regulatory guidance.
How EEXI and CII Are Calculated
Understanding how EEXI and CII are calculated is essential for compliance and fleet planning. EEXI is a one-time design-based metric, while CII is calculated annually based on operational carbon output. If you're looking for an easy way to explore emissions profiles across different ship types, try our Maritime Decarbonization Calculator to test fuel options, voyage speeds, and emission reductions.
How These Metrics Are Calculated
Regulation
Main Formula or Input
What It Measures
EEXI
CO₂ emissions per ton-mile based on design speed, deadweight, installed power, and engine/fuel type
How energy-efficient a ship is *by design* — like a fuel economy rating for an existing vessel
CII
Annual CO₂ emissions ÷ total transport work (cargo x distance)
Real-world *carbon intensity* — how much CO₂ your ship emits per mile of cargo carried
Compliance Benchmark
EEXI must be below a required limit set by ship type and size
CII rating must stay at C or above to avoid mandatory improvement plans
Note: These calculations are based on IMO guidelines under MARPOL Annex VI and verified performance data.
Penalties and Business Impact
Failure to meet EEXI and CII standards isn’t just a regulatory issue, it affects your bottom line. From ship detention to lost charter value, the penalties can escalate quickly. Below, we break down the specific risks of non-compliance and the broader financial consequences across the maritime supply chain.
⚠️ EEXI Non-Compliance Penalties
Ship may be denied renewal of its International Energy Efficiency Certificate (IEEC)
Port state control detention risk for missing or invalid technical file
Delays in retrofitting or derating engines can block voyage planning
Potential insurance complications or surcharges
📉 CII Poor Rating Consequences
Two consecutive D ratings or one E rating triggers corrective action plan
Charterers increasingly reject ships with D/E ratings due to ESG rules
Banks and investors may apply higher risk premiums
Some flags and regulators may issue warnings or limit trade areas
Wider Business Impact
Stakeholder
Impact
Example
Shipowner
Lower resale value and increased compliance costs
Older bulkers see resale value drop 10–15% if unrated or D/E rated
Charterer
Limited pool of compliant ships to choose from
Many 2025 contracts now require a C-rating or better
Investor / Bank
Higher lending scrutiny based on carbon risk
Poseidon Principles tie loan terms to emissions performance
Note: Based on verified 2025 industry ESG disclosures, charter standards, and financial ESG frameworks.
What You Can Do to Comply with Both
Meeting both EEXI and CII requirements takes more than a one-time adjustment. Below are actionable tactics that shipowners and operators are using to stay compliant, without breaking the bank.
🛠 Engine Power Limitation (EPL)
Reducing the maximum engine output helps meet EEXI limits without major retrofits. Often implemented via override software or shaft power limitation systems.
⚡ Improve Voyage Planning
Use optimized routing and weather tools to avoid delays and improve fuel efficiency, reducing your CII score without hardware changes.
⛽ Switch to Lower-Carbon Fuel
Fuels like LNG, methanol, or biofuels can drastically lower emissions and help with both EEXI and CII performance. Some ports offer incentives for green fuel use.
📊 Use Performance Monitoring Systems
Digital twins, AI routing, and onboard monitoring tools provide real-time CII feedback and suggest mid-voyage adjustments to stay within targets.
📄 File a Corrective Action Plan (if Needed)
If your vessel receives a D or E rating, prepare and submit a corrective plan to your flag state. This shows good faith compliance and can mitigate penalties.
What’s Changing in 2025 and Beyond
EEXI and CII aren’t standing still. Several regulatory updates and industry shifts are already shaping the next phase of compliance and the pressure is rising from all sides. Here’s what’s coming next, and how it might affect your operations.
Upcoming Regulatory & Market Changes
Change
Timeline
Impact
EU ETS Expansion to Shipping
Fully phased in by 2026
Carbon emissions from voyages to/from EU now incur €45–€100/tCO₂ costs
Stricter CII Thresholds
Starting Jan 2026
Annual CII performance grades will tighten; more vessels risk falling into D or E
Carbon Intensity Target (IMO)
30% cut by 2030
Global target applies across all ship classes; pressure to retrofit or optimize fleet
Green Corridors & Fuel Mandates
2025–2030
Certain routes (e.g. Singapore–Rotterdam) may soon require low- or zero-carbon fuels
CII Expansion to Smaller Vessels
Expected by 2026–2027
Regulations may soon apply to vessels under 5,000 GT, widening the compliance scope
Note: Based on verified 2025 IMO proposals, EU regulations, and port policy announcements.
Navigating EEXI and CII doesn’t have to be overwhelming. While the regulations are evolving, most shipowners already have tools at their disposal to stay ahead. By taking proactive steps now, like improving fuel efficiency, monitoring carbon intensity, and using data-driven voyage planning, you not only comply with the rules but also improve your competitiveness.
As 2025 brings tighter thresholds and carbon pricing mechanisms, understanding the cost-benefit landscape of compliance actions becomes even more critical. Here’s a quick reference table to help you make informed decisions:
Compliance Strategy Guide (2025+)
Compliance Action
Helps With
Estimated Cost
Operational Benefit
Engine Power Limitation (EPL)
EEXI
$10,000–$50,000 per vessel
Fastest path to EEXI compliance for existing tonnage
Hull Cleaning & Propeller Polishing
Both
$3,000–$10,000 per vessel (quarterly)
Improves fuel efficiency by up to 10%
Voyage Optimization Software
CII
$15,000–$50,000 per year
Real-time emissions tracking, weather routing, speed control
Biofuel or LNG Blending
Both
20–50% higher OPEX vs. conventional fuel
Reduces CO₂ intensity while meeting client ESG targets
Installing Shaft Power Limitation (ShaPoLi)
EEXI
$40,000–$80,000 per vessel
Alternative to full engine retrofit; simple compliance lever
Data Monitoring Systems (e.g. Noon Reports)
CII
$5,000–$20,000 per year
Enables corrective decisions mid-voyage to preserve CII score
Fleet-Wide ESG Strategy Alignment
Both
Varies — strategic initiative
Improves access to charter contracts and green financing
Note: Based on verified 2024–2025 industry compliance benchmarks and cost data.
