The biggest ways to reduce shipping emissions are not the visible ones. A business can switch to recycled cartons and still produce far more emissions from one avoidable air shipment than from a year of packaging. To rank the levers, this guide uses the UK government's official freight emission factors for 2026, shows the arithmetic with made-up shipments, and then sets out the rules that shape carrier choices, including the IMO's strategy for ships and the EU's emissions trading for shipping, and the measures India has announced for rail freight. The factors are averages used for UK company reporting, so treat them as a guide to relative scale, and ask your carrier for its own data when you need a figure for your lane.
For reporting methods, see transportation emissions reporting standards. For the broader picture, see green logistics and reducing your carbon footprint.
What the Official Factors Show
The Department for Energy Security and Net Zero publishes conversion factors for company greenhouse gas reporting. Its 2026 edition, published on 11 June 2026 with a flat file revised on 31 July 2026, has a Freighting goods sheet. The values below are in kilograms of carbon dioxide equivalent per tonne-kilometre, that is, per tonne of goods carried for one kilometre.
| Mode (as labelled in the sheet) | kg CO2e per tonne-km | Compared with container ship (average) |
|---|---|---|
| Container ship, average | 0.01612 | 1.0 times |
| Freight train | 0.02583 | 1.6 times |
| Heavy goods vehicle, average non-refrigerated, average laden, all diesel | 0.10356 | 6.4 times |
| Freight flight, international, including indirect effects of non-CO2 emissions | 0.89939 | 55.8 times |
| Freight flight, international, excluding those indirect effects | 0.5313 | 33.0 times |
The sheet notes that aviation has direct and indirect climate effects and says organisations should include the indirect effects when reporting air freight, while noting that there is significant scientific uncertainty about their size. It also says the factors include a distance uplift of 8% for flights that do not take the most direct route. Within container shipping the sheet shows a clear size effect: the average is 0.01266 for ships of 8,000 TEU and above, 0.02025 for 2,000 to 2,999 TEU and 0.03675 for ships below 1,000 TEU.
Example 1: Mode Choice for a Made-Up Shipment
A shipper moves 5 tonnes over a made-up distance of 3,000 kilometres. The emissions are the tonnes times the distance times the factor.
| Choice | Calculation | Result |
|---|---|---|
| All by sea | 5 x 3,000 x 0.01612 | 241.8 kg CO2e |
| All by air, with indirect effects | 5 x 3,000 x 0.89939 | 13,490.9 kg CO2e |
| 20% by air and 80% by sea | 0.2 x 13,490.85 + 0.8 x 241.8 | 2,891.6 kg CO2e |
Sending only the urgent 20% by air and the rest by sea cuts emissions by 78.6% compared with sending everything by air (1 minus 2,891.61 divided by 13,490.85). The mode share, not the packaging, decides the result. Planning earlier is therefore a carbon decision as well as a cost decision, as our guide to air freight vs sea freight explains.
Example 2: A Long Inland Leg by Rail
A made-up consignment of 10 tonnes travels 1,400 kilometres inland. By heavy goods vehicle the emissions are 10 x 1,400 x 0.10356, which is 1,449.8 kg CO2e. By freight train they are 10 x 1,400 x 0.02583, which is 361.6 kg CO2e, a saving of 75.1%. A train can need a truck at each end, so assume 140 kilometres by road and 1,260 by rail: 10 x 140 x 0.10356 is 145.0 kg and 10 x 1,260 x 0.02583 is 325.5 kg, a total of 470.4 kg, which is still 67.6% below the all-truck figure. The saving depends on the route and the terminals available, which our guide to sea-road vs sea-rail freight covers.
India has set a target in this direction. A PIB backgrounder of 16 August 2025 says the government aims to raise the railways' share of freight from 35-36% to 45% by 2030, that the Freight Greenhouse Gas Calculator has been developed to compare transportation cost and emissions, and that Indian Railways has launched Rail Green Points for freight customers so that they can see potential carbon emission savings.
Example 3: The Same Cargo on Different Ship Sizes
The sheet's container ship factors fall as the ship gets larger. For the made-up 5 tonnes over 3,000 kilometres from Example 1, a ship of 8,000 TEU and above at 0.01266 gives 5 x 3,000 x 0.01266 = 189.9 kg CO2e, while a ship below 1,000 TEU at 0.03675 gives 5 x 3,000 x 0.03675 = 551.3 kg CO2e, which is 2.9 times as much. The average of 241.8 kg sits between the two. A shipper cannot always choose the ship, but a forwarder can tell you which service you are booked on and whether it runs larger vessels. Size is only one factor: the sheet's factors are averages and do not describe a particular voyage.
Six Levers, Ranked by Size in the Examples
- Avoid air freight that planning could avoid. It has the largest factor in the table.
- Move long inland legs by rail where a terminal is close. The factor is about a quarter of the truck figure in the table.
- Consolidate and fill containers. Fewer part-empty movements mean less fuel for the same cargo. See how cargo consolidation helps manage shipping costs.
- Prefer services on larger ships where the schedule allows. The sheet's averages fall as ship size rises.
- Reduce weight and volume. Lighter, tighter packing lowers the tonnes or the containers moved.
- Ask for emissions data per shipment. A figure from your carrier's own fuel data is better than an average. The sheet itself says that, where possible, users should report litres of fuel or kWh of electricity used rather than rely on distance-based factors.
The Rules Behind Carrier Choices
The IMO's 2023 Strategy sets levels of ambition for international shipping: net-zero greenhouse gas emissions by or around 2050, a reduction of at least 20% (striving for 30%) by 2030 and at least 70% (striving for 80%) by 2040 compared with 2008, a cut in carbon intensity of at least 40% by 2030 and at least 5% (striving for 10%) of energy from zero or near-zero greenhouse gas fuels by 2030. The Energy Efficiency Existing Ship Index and the Carbon Intensity Indicator ratings entered into force on 1 January 2023. The proposed Net-Zero Framework was not adopted in October 2025, when the IMO committee agreed to adjourn the session and to reconvene in 12 months, as the IMO's press briefing records.
The EU Emissions Trading System has applied to shipping since 1 January 2024, with a phase-in of 40% in 2024, 70% in 2025 and 100% from 2026, according to UNCTAD's Review of Maritime Transport 2025, which adds that carriers apply surcharges to EU-related routes. It does not govern a China to India voyage, but it shows how carbon rules reach prices.
What to Ask a Carrier or Forwarder
- Which factor set and year do you use, and can you show the calculation?
- Do you report air freight with and without the indirect effects?
- Can you give shipment-level fuel data rather than an average?
- What service options use larger ships, and what do they change in the schedule?
- Which part of the inland leg could move by rail?
A Simple Measurement Routine
- List your shipments for a quarter with weight, mode and distance.
- Choose one factor set, state its source and year, and apply it to every shipment.
- Show air freight with and without indirect effects, as the sheet describes.
- Replace averages with carrier data where you can get it.
- Track the tonnes by mode each quarter, because the mode share is the number you control.
Reduce Shipping Emissions With RR Brothers and Logistics
RR Brothers and Logistics arranges sea freight and air freight from China, road freight to inland India and customs clearance. Tell us which shipments are urgent and which can wait and we will discuss how to plan the mode split.
Frequently Asked Questions
Avoiding air freight that planning could avoid. In the UK government factors for 2026, international freight flights are 55.8 times the container ship average per tonne-kilometre when indirect effects are included.
The UK factors give 0.02583 kg CO2e per tonne-kilometre for freight trains and 0.10356 for average laden heavy goods vehicles. In the made-up example, rail with short road legs was 67.6% lower.
One includes the indirect climate effects of non-CO2 emissions and one excludes them. The UK sheet says organisations should include the indirect effects when reporting, while noting scientific uncertainty about their size.
They are UK government factors published for UK company reporting, so use them as a guide to relative scale and ask carriers for lane-specific data when you need a precise figure.
The IMO's 2023 Strategy aims at net-zero greenhouse gas emissions from international shipping by or around 2050, with checkpoints of at least 20% by 2030 and at least 70% by 2040 compared with 2008.
A PIB backgrounder says the government aims to raise the railways' share of freight from 35-36% to 45% by 2030 and that Indian Railways has launched Rail Green Points for freight customers.
Sources
- UK Department for Energy Security and Net Zero: Greenhouse gas reporting, conversion factors 2026
- PIB: Logistics, India's growth engine (backgrounder, 16 August 2025)
- IMO: IMO's work to cut GHG emissions from ships
- IMO: IMO net-zero shipping talks to resume in 2026 (17 October 2025)
- UNCTAD: Review of Maritime Transport 2025
This article is general information, not legal, tax or customs advice. Rules, rates and procedures change; confirm current requirements with the relevant authority or a licensed customs professional before you ship. Regulatory references were checked against the official sources listed above on 28 October 2026.
Image credits: header photo by Wolfgang Weiser on Unsplash; photo by Aron Yigin on Unsplash. Used under the Unsplash License.
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