How the EU ETS Calculation Works

Last updated: September 2025

This page explains in detail how our ETS Calculator estimates carbon dioxide (CO₂) emissions for maritime voyages, determines the share that is subject to the EU Emissions Trading System (EU ETS), and translates that into an indicative compliance cost.

Important: the calculator provides indicative results for informational purposes only and does not replace regulatory compliance, official monitoring, reporting and verification (MRV), or professional advice.

1) CO₂ Emissions from Fuel Consumption

We estimate CO₂ emissions based on fuel mass and the default emission factors used in the EU MRV framework. Each maritime fuel has a characteristic carbon content that translates into a specific amount of CO₂ per tonne of fuel burnt.

Heavy Fuel Oil (HFO) — 3.114 tCO₂/t
Light Fuel Oil (LFO) — 3.151 tCO₂/t
Marine Gas Oil (MGO) — 3.206 tCO₂/t
Liquefied Natural Gas (LNG) — 2.750 tCO₂/t
Liquefied Petroleum Gas (LPG, propane/butane) — ~3.000 tCO₂/t

Formula: CO₂ (t) = Fuel consumed (t) × Emission factor (tCO₂/t).

2) Geographic Scope of the EU ETS

Under the EU ETS, maritime emissions are counted differently depending on the voyage pattern:

100% of emissions for voyages between EU ports (intra-EU).
50% of emissions for voyages between an EU port and a non-EU port (extra-EU legs).
Emissions at berth in an EU port are fully covered.

The calculator applies these percentages on a per-voyage basis. If an itinerary includes multiple legs, each leg is assessed according to the corresponding coverage rule.

3) Phase-in Percentages (Transitional Coverage)

EU ETS obligations for maritime emissions are phased-in over several years:

Reporting year	Share subject to the EU ETS
2024 emissions (surrender 2025)	40%
2025 emissions (surrender 2026)	70%
2026 and onwards	100%

From 2026, CH₄ and N₂O are also included in the ETS, in addition to CO₂.

4) Indicative ETS Cost

The indicative cost results from multiplying the ETS-covered emissions by the market price of EU Allowances (EUA).

Formula

Cost (€) = Taxable CO₂ (t) × EUA price (€/tCO₂)

The EUA price varies daily on the market (e.g., EEX).

5) EEOI (Operational Efficiency Indicator)

As an optional indicator, we compute the EEOI (Energy Efficiency Operational Indicator), according to IMO guidance, which measures efficiency in terms of CO₂ per tonne-nautical-mile transported.

Formula

EEOI = Total CO₂ (t) / [Cargo (t) × Distance (nm)]

EEOI is not part of the EU ETS but is useful for assessing operational performance.

6) Assumptions & Limitations

Default EU MRV emission factors are used unless specified otherwise.
Geographic coverage rule: 100% intra-EU / 50% extra-EU.
Phase-in coverage: 40% (2024), 70% (2025), 100% (from 2026).
From 2026, CH₄ and N₂O are included in addition to CO₂.
Results are indicative and do not replace verified MRV data.

Simplified assumptions do not cover all operational complexities (e.g., multi-fuel operations, vessel-specific factors).

References

EU ETS for Maritime Transport — European Commission
Scope and phase-in rules.
EU MRV Regulation — Default Emission Factors
Standard CO₂ emission factors per fuel.
IMO MEPC.1/Circ.684 — EEOI Guidelines
Operational efficiency indicator.