Free tool
CII rating estimator
Annual fuel, distance sailed and deadweight in — attained CII, the year's required CII and the A-E band out, with the arithmetic shown. Every coefficient is taken from the IMO instruments (MEPC.353(78) reference lines, MEPC.354(78) rating boundaries, MEPC.400(83) reduction factors) and the sources are cited below. Runs entirely in your browser; nothing you enter is sent anywhere.
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- Reference lines: MEPC.353(78) Table 1 — bulk carrier a=4745, c=0.622 (capacity capped at 279,000 DWT); tanker 5247 / 0.610; container 1984 / 0.489; general cargo ≥20,000 DWT 31948 / 0.792, below 588 / 0.3885.
- Rating boundaries: MEPC.354(78) dd vectors — bulk 0.86/0.94/1.06/1.18 · tanker 0.82/0.93/1.08/1.28 · container 0.83/0.94/1.07/1.19 · general cargo 0.83/0.94/1.06/1.19.
- Reduction factors: MEPC.400(83), adopted April 2025 — 2026: 11% · 2027: 13.625% · 2028: 16.25% · 2029: 18.875% · 2030: 21.5% (2024: 7%, 2025: 9%).
- Deliberately out of scope: gas / LNG / ro-ro types (parameters not yet verified to our standard), G5 voyage-adjustment correction factors, and any fuel not listed. The verified DCS figure prevails over this estimate.
Questions
Why does the tool cover only four ship types?
Because those are the four whose reference-line parameters and rating boundaries we have verified against the primary sources — MEPC.353(78) Table 1 read from the official IMO document, and MEPC.354(78) boundary vectors cross-checked against classification society guidance. Gas, LNG and ro-ro segments use different, partly piecewise parameters we have not yet verified to the same standard, and we do not publish numbers we have not verified.
Is this the same figure my DCS verifier will report?
Not necessarily. This estimator computes the basic attained CII from total fuel, CF factors, capacity and distance. The regulatory figure comes from your verified IMO DCS data and may apply correction factors and voyage adjustments (G5) that this tool deliberately does not model. Use it to see where you stand and to test scenarios, not to file anything.
What changed for 2026-2030?
MEPC 83 (April 2025) adopted the reduction factors beyond 2026: 13.625% (2027), 16.25% (2028), 18.875% (2029) and 21.5% (2030) against the 2019 reference line, with 2026 at 11%. Practical effect: a vessel rated C today drifts toward D on the same performance — the boundaries move even if the ship does not.
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