CII calculator

The CII calculator works out this year’s Carbon Intensity Indicator rating — A (major superior) to E (inferior) — from the fuel burnt in the year and the distance sailed, for twelve CII ship types (bulk carrier, tanker, gas carrier, LNG carrier, container ship, general cargo, refrigerated cargo, combination carrier, two kinds of ro-ro cargo ship, ro-ro passenger and cruise). It uses the IMO fuel conversion factors, reference lines, rating bands and the reduction factors for 2023 to 2030, and names the resolution each one comes from.

The result shows the attained CII against the required CII (in grams of CO2 per deadweight- or gross-tonnage-mile), the rating on a coloured A–E bar with a black marker for your ship, the CO2 emitted, the 2019 reference line, the reduction factor for the year and the four band boundaries. A D or E rating shows a note that D three years in a row, or E once, needs a corrective action plan in SEEMP Part III.

It is a planning aid. The official rating comes from your flag or its recognised organisation using the verified DCS data, and this calculator does not apply the voyage adjustments and correction factors of the IMO G5 guidelines, so the company’s official figure may differ.

Everyone, on every plan including Free. Works offline; nothing leaves the phone.

1. Open "CII calculator" from the Calculators group of the menu.
2. Choose the "Ship type (CII category)" (pre-selected from your vessel’s ship type) and the "Year" (2023 to 2030, each with its percentage below the 2019 line).
3. Enter the deadweight at summer draught, or the gross tonnage for the GT ship types, and the "Distance sailed in the year (nautical miles)".
4. Under "Fuel burnt in the year", pick the fuel and type the tonnes as reported for the IMO DCS; tap "Add another fuel" for each extra fuel.
5. Read the rating, the attained-versus-required line and the band bar; open "How this is worked out" for the formula, the yearly factors and the sources.

• Use the same fuel tonnes and distance as the DCS report, split by fuel grade — the conversion factor differs between heavy fuel oil, diesel and LNG.
• If the result is D or E, read the "The Master must" box under CII in the Quick reference: know the rating, the trend and the corrective action plan before an inspection.

• Your inputs are remembered on this phone only (a working figure, not a ship record) and are not shared with anyone.
• The 2027–2030 reduction factors are the ones adopted at MEPC 83; the screen carries an "unconfirmed" note saying a later IMO review may change them — check your flag or class notice before relying on them.
• Not the official rating; no voyage adjustments or correction factors are applied.