Last updated: 4 November 2026

Per passenger, a freighter crossing almost always has a smaller carbon footprint than a long-haul flight or a cruise, but the exact number depends on how you count it. A London–New York return flight in economy is about 1.3 tonnes CO2e using UK government factors. A cruise both ways is roughly double that in CO2. A freighter passenger adds very little fuel, yet no official factor exists for them.

Why comparing a freighter with a flight is tricky

A plane or cruise ship exists to carry people. Its fuel is shared between passengers, so per-passenger factors are straightforward. A container ship exists to carry cargo. It would sail on the same schedule if every cabin were empty.

That raises a fair question. Should a passenger take a share of the ship’s fuel at all? Dr Tristan Smith of UCL has argued that freighter passengers carry little to no share of the CO2, because freight is the ship’s main purpose. Other people prefer a cautious allocation, so the trip is not presented as “free”. Both views are defensible. What matters is saying which one you use.

The numbers: flight, cruise and container ship

These are the factors we use. Each comes from a named source. Note that they do not all measure the same thing: some are CO2 only, some are CO2e, and only the flight factor includes non-CO2 effects.

The ICCT points out that flying’s total climate effect, including contrails, may be around three times its CO2 alone, though this is uncertain. That is why DESNZ publishes flight factors with and without radiative forcing. The 2026 DESNZ edition gives almost the same economy figure (0.11704).

Watch: how shipping is trying to cut emissions

Worked example: London to New York and back

We use a great-circle distance of about 5,540 km each way, so 11,080 km return. For fairness, we apply the same distance to every mode. Real sea routes are longer, and transatlantic freighters usually sail from continental ports such as Antwerp or Hamburg rather than London. Treat every figure below as an estimate.

A common real-world pattern is freighter one way and a flight back. That would be roughly half the flight figure, about 650 kg CO2e with RF, plus the freighter share. Remember the longer trip also means more days of food and onboard power, which some methods would count.

Four ways to count a freighter passenger

Each method answers a slightly different question. Marginal accounting asks what changes because you booked. Mass share treats you like cargo. A passenger proxy borrows the closest official factor. A cabin share splits the ship’s “hotel” energy between the few guests, which gives a higher figure on small accommodation decks.

Watch: can ships run on renewable power?

What the shipping industry is doing about it

Shipping is not clean overall. It burns large volumes of heavy fuel, as our guide to how much fuel a container ship uses explains. In 2023 the IMO adopted a revised strategy: net zero greenhouse gas emissions by or around 2050, with checkpoints of at least 20% cuts by 2030 and 70% by 2040 against 2008 levels.

The tool meant to deliver this is the IMO Net-Zero Framework, a global fuel standard with carbon pricing. In October 2025 member states voted 57 to 49 to adjourn its adoption for a year. At MEPC 84 in April 2026 it was kept as the basis for talks but still not adopted. The next attempt is planned for MEPC 85 in December 2026. Meanwhile, lines are ordering dual-fuel ships that can run on methanol or LNG, and many ships are slow steaming to save fuel.

Cargo ship vs flight vs cruise at a glance

Tips

1. Book a freighter one way and stay longer at your destination, rather than flying out and back twice.
2. If you fly, choose economy: DESNZ business-class factors are around three times higher.
3. When you quote a figure, state the method and whether radiative forcing is included.
4. Ask the line about ship age and fuel; newer dual-fuel ships may perform better.
5. Check crossing times in our guide to how long it takes to cross the Atlantic by ship.
6. Do not buy offsets as a substitute for travelling less; treat them as a last step.

Foire aux questions

Sources: UK DESNZ Greenhouse gas reporting conversion factors 2025 and 2026; ICCT analysis of cruise emissions; UCL (Dr Tristan Smith) on freighter passengers; IMO 2023 GHG Strategy; DNV and Carbon Brief on the IMO Net-Zero Framework. All figures are estimates. Checked November 2026.