EEOI — Energy Efficiency Operational Indicator

Calculate voyage EEOI using IMO definition: EEOI = Total CO₂ / Transport Work.

Notes
Single Voyage Parameters
Fuel Components
Fuel preset Fuel (t) EF (tCO₂/t) Remove
CO₂ = Σ (Fuel × Emission Factor)
Multi-Leg Voyage Table
Leg Distance (nm) Cargo (t) Fuel preset Fuel (t) EF (tCO₂/t) Remove
Set cargo = 0 for ballast legs.
Direct Input
EEOI Result

Total CO₂: — t

Transport work: — t·nm

EEOI: — g CO₂ / (t·nm)

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EEOI — Energy Efficiency Operational Indicator

The EEOI is an IMO operational efficiency metric that relates a vessel’s CO₂ emissions to the transport work performed. It is commonly used for internal KPI tracking, SEEMP reporting workflows, and comparing performance between voyages, routes, or operating profiles. This calculator supports single-voyage, multi-leg, and direct input use cases.

EEOI formula

This tool uses the IMO-style definition:

EEOI = Total CO₂ / Transport work

Total CO₂ (t) = Σ (Fueli (t) × EFi (tCO₂/t))

Transport work (t·nm) = Σ (Cargo (t) × Distance (nm))

The calculator outputs EEOI in: g CO₂ / (t·nm). Internally it converts tonnes of CO₂ to grams using: 1 t = 1,000,000 g.

What “transport work” means

Transport work is the amount of cargo moved over a distance. For a simple voyage with constant cargo:

  • Single-voyage: Transport work = Cargo × Distance
  • Multi-leg: Transport work = Σ(Cargoleg × Distanceleg)

If the vessel sails ballast legs, you can set cargo to 0 for those legs (this is common in operational tracking). Make sure your approach matches your company’s reporting policy.

How to use this calculator

Mode A — Single voyage

  1. Enter Distance (nm) and Average Cargo (t).
  2. Add one or more fuel components (mix fuels if needed).
  3. For each component, enter Fuel (t) and confirm EF.
  4. Calculate to get Total CO₂, Transport work, and EEOI.

Mode B — Multi-leg voyage

  1. Add legs (or load a sample table).
  2. For each leg, enter Distance, Cargo, Fuel, and EF.
  3. Use cargo = 0 for ballast legs if applicable.
  4. The tool sums CO₂ and transport work across all legs.

Mode C — Direct input

  1. Enter known Total CO₂ (t).
  2. Enter known Transport work (t·nm).
  3. Calculate EEOI instantly (useful for audits or external reports).

Fuel presets & emission factors

Emission factors (EF) represent tonnes of CO₂ emitted per tonne of fuel burned (tCO₂/t). This calculator provides presets for common marine fuels as a convenience. You should always verify EF values against your company’s standard, the applicable IMO/industry guidance, and the required reporting boundary (tank-to-wake vs well-to-wake).

  • Fuel mix: Use multiple components when bunkers include more than one fuel grade.
  • Overrides: You can edit EF manually per row to match your reference source.
  • Consistency: Compare voyages only if EF sources and cargo accounting method are consistent.

Common pitfalls & practical tips

Data quality

  • Use the same distance basis across voyages (planned vs logged vs great-circle/rhumbline).
  • Use consistent cargo definition (cargo carried, deadweight used, or “transported cargo”).
  • Ensure fuel mass is in tonnes and EF in tCO₂/t.
  • When splitting legs, keep leg fuel aligned with leg distance/cargo.

Interpreting EEOI

  • Lower EEOI generally indicates better operational efficiency.
  • EEOI is sensitive to ballast time, slow steaming, and cargo utilization.
  • Compare within similar trade patterns and seasons for best insight.
  • Track EEOI with supporting KPIs (fuel t/day, speed, weather) to explain changes.

Worked example (quick)

Suppose a vessel carries 12,500 t cargo over 1,650 nm. It burns 85 t of VLSFO with EF 3.114 tCO₂/t.

  • Total CO₂ = 85 × 3.114 = 264.69 t
  • Transport work = 12,500 × 1,650 = 20,625,000 t·nm
  • EEOI = (264.69 × 1,000,000) / 20,625,000 ≈ 12.83 g CO₂/(t·nm)

Your result will differ if you change cargo accounting, distances, or EF source—keep your method consistent across comparisons.

Related calculators

EEOI is usually part of a wider operational efficiency workflow. These tools help you build the full chain from fuel use to emissions and voyage KPIs:

CO₂ Emission Estimator
Convert fuel consumption into CO₂ totals using EF and fuel mixes.
Fuel Consumption
Estimate tonnes burned from power, SFOC, distance, speed, and voyage profile.
SFOC Calculator
Estimate specific fuel oil consumption at a given engine load and plot the curve.
Fuel Cost Calculator
Convert tonnes to total cost using price, density corrections, and fees.
ETA Calculator
Estimate time from speed and distance—useful when building voyage assumptions.
Effective Power (PE)
Link resistance and speed to power—useful for fuel and emissions estimates.

FAQ

No. EEOI is an operational indicator based on actual voyage performance. EEDI is a design index, and CII is a regulatory operational rating framework with specific rules and boundaries. EEOI is often used internally to understand and improve day-to-day efficiency.

Use the cargo definition that matches your reporting method (e.g., actual cargo carried, average cargo for the leg, or another company-defined proxy). The key is consistency—use the same definition when comparing voyages.

Many operators track voyage-only, while others include port consumption depending on KPI definition. If you include port fuel, ensure the transport work boundary remains meaningful and apply the same method across all voyages.

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