IMO EEOI • Voyage CO₂ Intensity • Transport Work • Fuel CF • Ballast Emissions • Multi-Voyage Period • Rolling Average • Fuel Mix • Target Sensitivity

EEOI Tool Energy Efficiency Operational Indicator & Voyage Carbon Intensity

Calculate operational CO₂ efficiency as emissions per unit of transport work using the IMO EEOI method. Simple mode handles one transport voyage with up to two fuels. Advanced supports transport, ballast and other zero-work legs, up to three fuels per row, official EEOI fuel conversion factors plus a custom factor, weighted period EEOI, rolling weighted EEOI, emissions-by-fuel analysis and fuel/work sensitivity without incorrectly averaging individual voyage EEOIs.

Figures represent
Need ballast legs, multiple voyages or rolling performance? Click Advanced above.Advanced follows the period formula: total included CO₂ divided by total transport work. Ballast/zero-work legs can contribute fuel and CO₂ without adding transport work to the denominator.
Fast8 primary inputs
Core outputg CO₂ per unit-nm
ImportantEEOI is not the MARPOL CII rating

Single-Voyage EEOI

For a single transport voyage, enter total fuel consumed for the defined voyage at sea and in port. Use Advanced when the analysis needs explicit ballast/zero-cargo legs or multiple voyages.

tonnes cargo.
nautical miles.
metric tonnes.
metric tonnes; set fuel type to None if unused.
g CO₂ per tonne-nm. User-entered comparison only.

Period & Transport-Work Basis

g CO₂ per tonne-nm.
included rows used in weighted rolling EEOI.
t-CO₂/t-fuel. Use only when “Custom fuel” is selected; verify the appropriate accounting basis.

Voyage / Period Register

Transport rows require positive work amount. Ballast and Other Zero-Work rows carry zero transport work but their fuel/CO₂ remains in the period numerator. Safety / SAR rows are excluded from both numerator and denominator in this screen.

TypeWork amountDistance NMFuel 1Fuel 1 tFuel 2Fuel 2 tFuel 3Fuel 3 t

Data Quality & Monitoring Readiness

Method boundary: EEOI is an operational CO₂/transport-work indicator under IMO’s voluntary EEOI guidance. It is not the IMO CII attained annual operational carbon-intensity rating and does not produce an A–E CII grade. The default fuel conversion factors are the carbon-content factors listed in MEPC.1/Circ.684; newer/alternative fuels can require a different verified factor or accounting framework. This tool reports tank-to-wake-style CO₂ from entered fuel mass × CF and does not calculate lifecycle/WtW GHG intensity.
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