Calculate direct combustion CO₂ from fuel mass, daily consumption, or SFOC and engine power.
Preset factors follow listed IMO fuel categories; use documented values for VLSFO, hybrid and unlisted fuels.
Total Fuel Mass: — t
Total CO₂: — t CO₂
Mass-Weighted CF: — t CO₂/t fuel
Total Duration: — h
Total Fuel: — t
Total CO₂: — t CO₂
Applied CF: — t CO₂/t fuel
Calculated Energy: — kWh
Calculated Fuel: — t
Total CO₂: — t CO₂
Applied CF: — t CO₂/t fuel
Direct carbon-dioxide emissions from fuel combustion can be estimated by multiplying the mass of each fuel consumed by its applicable mass-to-CO₂ conversion factor. This calculator performs that calculation from a known fuel quantity, a daily consumption rate, or fuel derived from SFOC, engine power and operating time.
The result is expressed as tonnes of CO₂. When several fuels are entered, each component is calculated separately before the emissions are summed.
The factor CF represents tonnes of CO₂ per tonne of fuel. It is dimensionless as a mass ratio, although it is commonly displayed as t CO₂/t fuel to make the input and output units clear.
Use the Total Fuel method when the consumed quantity is already known. Fuel may be entered directly as mass or converted from volume using an entered density.
The weighted factor is based on fuel mass. It is not the simple arithmetic average of the selected conversion factors.
Enter either mass or volume for each component. When volume is used, density should come from the bunker delivery documentation, laboratory result, custody-transfer data or another suitable source for the same fuel quantity and reference condition.
Use the Daily Consumption method when fuel use is known as tonnes per day over a defined period.
The calculator treats the entered daily rate as constant over the complete duration. It does not account for separate sea, port, manoeuvring or cargo-operation consumption rates unless these periods are calculated separately.
Use the SFOC method when fuel consumption is not known directly but engine power, operating time and specific fuel oil consumption are available for the same operating condition.
The factor 1,000,000 converts grams to tonnes. The entered SFOC should represent the actual or selected engine load. A shop-test SFOC at one load should not automatically be applied to a different operating condition.
| Symbol | Meaning | Unit |
|---|---|---|
| mfuel | Fuel mass consumed | t |
| Vfuel | Fuel volume | m³ |
| ρ | Fuel density used for volume conversion | t/m³ |
| CF | Fuel-mass to CO₂-mass conversion factor | t CO₂/t fuel |
| qdaily | Daily fuel-consumption rate | t/day |
| d | Whole days | day |
| h | Additional hours | h |
| P | Engine power used in the SFOC calculation | kW |
| t | Engine operating time | h |
| E | Calculated engine energy | kWh |
| SFOC | Specific fuel oil consumption | g/kWh |
| CO₂ | Calculated direct carbon-dioxide mass | t CO₂ |
The presets below follow the fuel categories and conversion factors listed in the IMO SEEMP data-collection guidance. They convert fuel mass to direct CO₂ mass.
| Fuel category | CF (t CO₂/t fuel) |
|---|---|
| Diesel / Gas Oil | 3.206 |
| Light Fuel Oil | 3.151 |
| Heavy Fuel Oil | 3.114 |
| LPG — Propane | 3.000 |
| LPG — Butane | 3.030 |
| Ethane | 2.927 |
| Liquefied Natural Gas | 2.750 |
| Methanol | 1.375 |
| Ethanol | 1.913 |
The conversion factors are not fuel-density values. Density is needed only when converting an entered volume to mass and can vary with fuel composition, batch and reference temperature.
A reporting period includes:
CO₂HFO = 100.000 × 3.114 = 311.400 t CO₂
CO₂DGO = 20.000 × 3.206 = 64.120 t CO₂
Total fuel = 100.000 + 20.000 = 120.000 t
Total CO₂ = 311.400 + 64.120 = 375.520 t CO₂
CF,weighted = 375.520 / 120.000 = 3.12933 t CO₂/t fuel
An engine operates with:
E = 5,000 × 24 = 120,000 kWh
Fuel = 180 × 120,000 / 1,000,000 = 21.6000 t
CO₂ = 21.6000 × 3.114 = 67.2624 t CO₂
Entering 21.6000 t HFO in the Total Fuel method should return the same 67.2624 t CO₂. This provides a direct cross-check between the two tabs.
Regulatory and operational CO₂ calculations use fuel mass. When only volume is known, mass is obtained from density:
For example, 100 m³ of fuel at 0.450 t/m³ corresponds to 45.000 t. With an LNG conversion factor of 2.750:
CO₂ = 45.000 × 2.750 = 123.750 t CO₂
This arithmetic does not confirm that 0.450 t/m³ is suitable for a particular delivery. Use the density applicable to the actual measurement and documentation.
The calculator includes:
LNG can have a lower direct CO₂ conversion factor than oil fuels while still producing additional climate effects through unburned methane. Those effects are outside this calculator.
A direct CO₂ factor of zero for a carbon-free fuel does not mean that production, transport or use of that fuel has zero lifecycle emissions.
Fuel mass multiplied by an applicable conversion factor is part of marine CO₂ reporting arithmetic. This calculator can be used to independently check that multiplication and mixed-fuel summation.
It does not collect or verify all data required for an IMO DCS or EU MRV submission. It does not determine reporting boundaries, voyage inclusion, fuel-measurement procedures, data gaps, verifier evidence or company-specific monitoring-plan requirements.
This calculator is intended for preliminary engineering, educational and independent arithmetic checks. It does not replace verified fuel data, an approved monitoring plan, supplier documentation, regulatory guidance or an accredited verification process.