How much more carbon does air freight emit than sea freight for an export order?
Per tonne-km, a long-haul air freighter emits about 72 times more than a container ship: 0.608 against 0.0084 kg CO2e on default factors. For a whole order the gap is smaller, about 25 times in the Mumbai to Frankfurt example below, because the sea route is longer and needs a road leg.
Why the per tonne-km gap is so large
An aircraft burns fuel to stay in the air and climbs with every kilogram it carries, while a large container ship moves thousands of boxes at low speed on a hull that floats. Default factors reflect this: a long-haul freighter is 0.608 kg CO2e per tonne-km, a container ship 0.0084. Short-haul air, below 1,500 km, is 1.516 per tonne-km, about 180 times the ship, because take-off and climb make up more of the trip.
Why the order level gap is smaller
- Air flies close to the great circle. The usual method adds 95 km to the great circle distance for routing and holding.
- Ships follow sea lanes, so Mumbai to Europe by sea is nearly twice the flight distance, more if the vessel goes around the Cape.
- Sea cargo usually needs a longer truck or rail leg at the European end, from Rotterdam or Hamburg to an inland buyer, and road freight has a much higher factor than the ship.
Weight and factor traps
- Use actual gross weight. The air waybill's chargeable weight can be a volumetric figure and overstates mass for light, bulky goods.
- Belly cargo on passenger flights and dedicated freighters have different factors; use the one that matches the flight if you know it.
- Say whether the air figure includes non-CO2 effects at altitude. The default factors do not; some buyers ask for them shown separately.
- Keep both modes on the same basis, well-to-wake, from the same factor set and edition.
A decision rule for urgent orders
If a buyer tracks supplier emissions, compare the extra air emissions with the order's other emissions before choosing. Splitting an order, flying only the urgent share and shipping the rest, often cuts most of the difference. Record the mode and reason on the shipment file so the figure you report later matches the paperwork.
Worked example: 500 kg order, Mumbai to a buyer in Frankfurt
- Air: great circle Mumbai to Frankfurt about 6,570 km + 95 km = 6,665 km
- Air: 0.5 t x 6,665 km = 3,332.5 tonne-km; x 0.608 (long-haul freighter) = 2,026.2 kg CO2e
- Sea: Nhava Sheva to Rotterdam about 11,700 km; 0.5 t x 11,700 = 5,850 tonne-km; x 0.0084 = 49.14 kg CO2e
- Road Rotterdam to Frankfurt about 450 km: 0.5 t x 450 = 225 tonne-km; x 0.1400 (medium truck) = 31.5 kg CO2e
- Sea door to Frankfurt: 49.14 + 31.5 = 80.64 kg CO2e
- Ratio: 2,026.2 / 80.64 = about 25 times
Factors are the long-haul freighter, container ship and medium truck default intensities, each well-to-wheel with typical empty running included. The medium truck value is the Indian default, used here only to show the arithmetic; a European carrier's factor will differ. The Indian road legs to the airport and port are left out because they are similar. Other factor sets give different values, so treat the ratio as a range, not one number.
What Senseible does here
Senseible reads freight records and applies weight x distance x mode factor when all three are printed; a record without weight or distance gets no figure. In the logistics calculator you can compare both routings leg by leg, per tonne-km by mode, with air split into short and long haul at 1,500 km. A carrier's own factor is used as given. Show any non-CO2 altitude effect separately if a buyer asks.
- Logistics emissions calculator
- One container, India to Europe
- Should flights include radiative forcing?
- GLEC Framework explained
Sources: GLEC Framework, logistics emissions accounting method, ISO 14083:2023, Quantification and reporting of greenhouse gas emissions arising from transport chain operations, UK DESNZ greenhouse gas conversion factors for company reporting, freighting goods
Last reviewed 2026-10-17.