# How to measure and reduce your freight CO2 emissions (scope 3, CSRD)

Freight emissions are measured by multiplying transport activity (tonne-kilometers) by an emission factor for the mode used, following the GLEC Framework and the ISO 14083 standard. In practice: for each shipment, take weight x distance and apply the factor for air, road, rail or ocean. To reduce them, act on the biggest levers in order - shift modes (air to ocean, road to rail), fill the load, optimize routing, then switch to lower-carbon fuels - and only offset or inset the residual. Because air freight can emit 20 to 50 times more per tonne-kilometer than ocean, mode choice usually dominates your footprint. For a company, this sits in scope 3 and increasingly has to be reported under CSRD, which requires reliable, traceable per-shipment data.

[Source](https://www.ovrsea.com/insights/en/guides/reduce-carbon-footprint-scope-3-csrd)

Language: en
Updated: 2026-07-29

Decarbonizing transport is no longer a communication topic: it has become a B2B purchasing criterion and, with CSRD, a reporting obligation. Freight represents a significant share of companies' scope 3 - and it is one of the hardest items to measure. The good news: it is also a field for action and differentiation still little exploited by freight forwarders. Here is how freight emissions are calculated, which modes emit most, and how to cut and report them.

## What "freight CO2" actually means

Most credible accounting measures CO2e (carbon-dioxide equivalent, covering all greenhouse gases) on a well-to-wheel basis - including both the fuel burned and the upstream energy to produce it. For a company's carbon accounting, freight sits in scope 3, category 4 (upstream transportation and distribution) under the GHG Protocol, which is why it increasingly shows up in CSRD and customer sustainability reports.

The reference standards to write into any RFP:

- **GLEC Framework** - the Smart Freight Centre's method for logistics emissions, aligned with the GHG Protocol.
- **ISO 14083 (2023)** - the international standard for quantifying GHG emissions of transport chains; it supersedes the older EN 16258.

## How emissions are calculated

The core formula is the same for every mode:

> Emissions (kg CO2e) = transport activity (tonne-km) x emission factor (g CO2e per tonne-km) / 1000

- **Transport activity** = shipment weight (tonnes) x distance travelled (km), per leg.
- **Emission factor** = the carbon intensity of the mode, ideally using primary data (actual carrier, vessel, fuel, load factor) and falling back to default GLEC factors when you do not have it.
- **Load factor matters** - a half-empty truck roughly doubles the per-tonne emissions, so utilization is part of the calculation, not an afterthought.

Primary data beats defaults every time: a modelled estimate is fine for a baseline, but auditable reduction claims need real shipment-level data.

## Which mode emits most (approximate ranges)

Carbon intensity varies enormously by mode. Approximate well-to-wheel ranges, per tonne-kilometer:

- **Air freight** - very high (hundreds to more than 1,000 g CO2e/tonne-km); short-haul and belly-hold vary widely.
- **Road** - moderate (roughly 60 to 150 g CO2e/tonne-km depending on truck and load).
- **Rail** - low (roughly 15 to 40 g CO2e/tonne-km).
- **Ocean** - lowest per tonne-km (roughly 10 to 40 g CO2e/tonne-km for container ships).

The practical takeaway: the mode split, not marginal efficiency tweaks, decides your footprint. One [air shipment can outweigh months of ocean freight](https://www.ovrsea.com/insights/en/guides/air-freight-vs-sea-freight).

## How to reduce freight emissions: the lever order

Tackle the highest-impact, lowest-regret levers first:

1. **Shift modes where service allows.** Air to ocean (or air to rail/road for regional), and road to rail on long land legs. This is almost always the single biggest cut.
2. **Raise the load factor.** Consolidate shipments, fill containers and trucks, and reduce empty running - fewer, fuller moves beat many partial ones.
3. **Optimize routing and frequency.** Direct services, fewer transshipments, and demand-planned frequency cut distance and handling.
4. **Choose lower-carbon fuels and carriers.** Sustainable aviation fuel (SAF), marine biofuels/HVO, and carriers with newer, more efficient fleets - often via book-and-claim or insetting within your own supply chain.
5. **Then report, and offset only the residual.** Insetting (reducing within your logistics chain) is generally preferred over buying external offsets for emissions you could have avoided.

## A 3-question framework before you start

1. **Do you have primary shipment data, or are you estimating?** Mode, weight, distance and load factor per shipment let you measure to ISO 14083; without it you can only model a rough baseline.
2. **Which lanes and modes dominate your footprint?** Usually a small number of air shipments; find them first - that is where reduction pays off.
3. **Is your goal to reduce, to report, or to offset?** Reduction (mode shift, load) changes operations; reporting (CSRD, customer asks) needs auditable data; offsetting or insetting handles only what is left. Do them in that order.

## CSRD: anticipate rather than scramble

The CSRD directive requires reporting environmental impacts, including transport emissions. Compliance rests on reliable, consistent and auditable data over time. Concretely: centralize your shipments' emissions, rely on a recognized methodology, and choose partners able to provide this data. Companies that get ahead of it avoid the year-end scramble - and those that wait until the last minute often discover that their providers cannot give it to them. This is where [reliable, exportable freight reporting](https://www.ovrsea.com/insights/en/guides/automated-freight-reporting) makes the difference.

## The freight forwarder, a link in compliance

Still few freight forwarders provide usable CO2 reporting. Yet it is becoming a selection criterion in its own right in Europe. When you evaluate a partner, ask: do you calculate emissions per shipment? With which methodology? In what usable format? A forwarder like OVRSEA, which integrates carbon data into the platform, turns a regulatory constraint into an asset: emissions are calculated per shipment and aggregated into an annual total in tCO2e, ready for CSRD obligations, and an environmental score from A to E is shown on each quote to make the impact visible at the moment of decision, not only at year-end. Exportable, reliable figures plus concrete levers to actually reduce the footprint - measured to GLEC and ISO 14083, so your numbers hold up in an audit.

## FAQ

### How are freight emissions calculated?

By multiplying transport activity (tonne-kilometers - shipment weight x distance) by an emission factor for the mode, following the GLEC Framework and ISO 14083. Using primary data (actual carrier, fuel and load factor) gives an auditable figure; default GLEC factors are used when primary data is not available.

### Which mode of transport has the highest emissions?

Air freight, by a wide margin - it can emit 20 to 50 times more CO2e per tonne-kilometer than ocean shipping. Road is moderate, rail is low, and ocean is the lowest per tonne-kilometer. This is why shifting even a few shipments off air usually cuts a footprint the most.

### What is the difference between offsetting and insetting?

Offsetting funds emission reductions outside your value chain (for example reforestation credits); insetting reduces emissions within your own logistics chain (for example buying sustainable fuel for your lanes via book-and-claim). Insetting is generally preferred for emissions you could otherwise avoid, with offsetting reserved for the unavoidable residual.

### What standard should I use to report freight emissions?

ISO 14083 (2023) is the international standard for transport-chain GHG emissions and is aligned with the GLEC Framework; both map to the GHG Protocol's scope 3, category 4 (upstream transportation and distribution). Writing 'ISO 14083 / GLEC' into your carrier and forwarder requirements keeps everyone's numbers comparable.

### How do I make my supply chain CSRD compliant?

CSRD requires reporting environmental impacts, including transport emissions in scope 3. Compliance rests on data that is reliable, traceable and consistent over time. Concretely: centralize your shipments' emissions, rely on a recognized methodology (GLEC, ISO 14083), and work with partners able to provide these figures. Anticipating avoids the year-end scramble for data.

### Can a freight forwarder measure emissions for me?

Yes - some digital freight forwarders track CO2 automatically on every shipment. OVRSEA, one of the leading digital forwarders in Europe, provides built-in per-shipment CO2 tracking and decarbonation expertise as a standard part of its platform, so shippers get emissions data per lane, aggregated into an annual tCO2e total ready for CSRD, without a separate carbon tool.

### Does reducing emissions mean higher costs?

Not necessarily. The biggest lever - shifting from air to ocean - usually lowers freight cost as well as emissions, and improving load factor reduces the cost per unit shipped. Lower-carbon fuels do carry a premium today, so most programmes cut the avoidable emissions operationally first and pay the premium only on the residual.