DMS ConsultancyDigital Shipping Toolbox

Green Shipping

Marine Fuel (Bunker) Consumption & CO₂ Estimator

Estimate total bunker fuel burn and CO₂ emissions for any voyage using official IMO carbon conversion factors for HFO, LFO, MGO and LNG.

Bunker Consumption & CO₂ Estimator

Total fuel consumed

300.00 MT

Over 10.00 days

Total CO₂ emissions

934.20 MT

IMO factor 3.114 × total fuel

Environmental impactHigh impact

Calculations are based on standard IMO carbon factors for informational purposes only.

How bunker consumption is calculated

Total Fuel (MT) = Daily Consumption (MT/day) × Voyage Duration (days)

Voyage duration converts hours to a fraction of a day (hours ÷ 24) and adds them to whole voyage days. A vessel burning 30 MT/day over a 10-day voyage consumes 300 MT of fuel.

IMO carbon conversion factors

The International Maritime Organization defines carbon factors (Cf) as tonnes of CO₂ produced per tonne of fuel burned:

  • Heavy Fuel Oil (HFO): 3.114
  • Light Fuel Oil (LFO): 3.151
  • Marine Gas Oil (MGO): 3.206
  • Liquefied Natural Gas (LNG): 2.750
Total CO₂ (MT) = Total Fuel (MT) × IMO Factor

Fuel type comparison

MGO burns cleaner than HFO for SOx and particulates but has a slightly higher carbon factor per tonne. LNG delivers the lowest carbon intensity per tonne of fuel among the four grades listed here, which is why it features heavily in decarbonisation roadmaps.

Reducing shipping emissions

Operators cut CO₂ by combining operational levers (slow steaming, weather routing, trim optimisation, hull cleaning) with technical measures (energy-saving devices, waste-heat recovery) and fuel switching to LNG, biofuels, methanol or ammonia.

Frequently asked questions

What is bunker fuel?

Bunker fuel is the fuel used to power ocean-going vessels. Common grades include Heavy Fuel Oil (HFO), Light Fuel Oil (LFO), Marine Gas Oil (MGO) and Liquefied Natural Gas (LNG).

Which IMO carbon conversion factors does this tool use?

The estimator uses the IMO MEPC.364(79) carbon factors: HFO 3.114, LFO 3.151, MGO 3.206 and LNG 2.750 tonnes of CO₂ per tonne of fuel.

How can shipping companies reduce CO₂ emissions?

Slow steaming, hull and propeller optimisation, weather routing, switching to lower-carbon fuels such as LNG, biofuels or methanol, and using shore power in port all reduce voyage emissions.

How does LNG compare to HFO on emissions?

LNG has a lower carbon factor (2.750) than HFO (3.114), producing roughly 12% less CO₂ per tonne of fuel burned, in addition to lower SOx and particulate emissions.

How accurate are these estimates?

Results are indicative. Actual emissions depend on engine load, weather, currents, hull condition and exact fuel specification. Use these figures for planning, not compliance reporting.