What is CII?
CII is the Carbon Intensity Indicator. It measures how much CO₂ a ship emits per unit of transport work over a year. IMO then compares that figure with a required line and gives a rating from A to E. The official rating depends on ship type, capacity and the year. This page only calculates a simple intensity number.
How this calculator works
CII ≈ (Fuel tonnes × Carbon factor × 1,000,000) ÷ (Capacity × Distance). Example: 2000 t HFO, 50000 DWT, 30000 NM gives about 4.152. Official CII uses DCS data, correction factors and the ship-type rating table. An A–E grade is not shown here because those bands change by ship type and year.
Who should use it
Useful for a voyage or annual estimate. For SEEMP Part III and class reporting, use only the official CII method and the company’s verified data.