- Scope 3 gathers the value chain's indirect emissions, beyond purchased energy, across 15 categories (8 upstream, 7 downstream).
- It is most often the largest part of the footprint, and the hardest to measure because it depends on data outside the company.
- You first estimate with monetary factors, then refine the largest categories with real data from priority suppliers.
- In the BEGES, it is mandatory only for companies subject to CSRD, but most customers and frameworks ask for it.
What is scope 3?
Scope 3 brings together a company's indirect emissions that fall neither under its direct sources (scope 1) nor under the energy it purchases (scope 2). These are the emissions generated upstream and downstream of its activity, all along its value chain: by its suppliers, its carriers, its employees who travel, and by the use then end of life of the products it sells.
The concept comes from the GHG Protocol, the international carbon accounting method. Its scope 3 standard, published in 2011, is the only method recognized worldwide for accounting for these value chain emissions. To situate scope 3 relative to the other two scopes, start with scopes 1, 2 and 3.
One point comes up in every footprint: according to the GHG Protocol, the largest share of a company's emissions most often comes from scope 3, not from its direct operations. Ignoring it means missing most of its carbon footprint.
What are the 15 scope 3 categories?
The GHG Protocol splits scope 3 into 15 categories: 8 upstream (what enters the company) and 7 downstream (what leaves it). Not all of them apply to your business, and the idea is not to fill in every one, but to identify those that matter.
| No. | Category | Upstream / Downstream |
|---|---|---|
| 1 | Purchased goods and services | Upstream |
| 2 | Capital goods (equipment, buildings) | Upstream |
| 3 | Fuel- and energy-related activities (outside scopes 1 and 2) | Upstream |
| 4 | Upstream transportation and distribution | Upstream |
| 5 | Waste generated in operations | Upstream |
| 6 | Business travel | Upstream |
| 7 | Employee commuting | Upstream |
| 8 | Upstream leased assets | Upstream |
| 9 | Downstream transportation and distribution | Downstream |
| 10 | Processing of sold products | Downstream |
| 11 | Use of sold products | Downstream |
| 12 | End-of-life treatment of sold products | Downstream |
| 13 | Downstream leased assets | Downstream |
| 14 | Franchises | Downstream |
| 15 | Investments | Downstream |
Depending on your sector, the weight concentrates on a few categories. A manufacturing company will mostly see purchases of materials (category 1) and use of sold products (category 11). A services company will mostly have purchases of services, travel and digital services. A bank or an insurer concentrates most of its footprint on investments (category 15). Measuring the footprint of a specific product is a different exercise, life cycle assessment, covered in our article on LCA and a product's carbon footprint.
Why is scope 3 so hard to calculate?
Because it depends on data you do not hold. Your energy or fuel consumption is on your bills. The emissions of a purchased component, of subcontracted transport, or of your product's use at the customer's site, you have to source elsewhere, from third parties that do not always measure them themselves.
The sheer size of this scope explains why it is so often neglected. According to a report by Boston Consulting Group and the CDP published in June 2024, supply chain scope 3 emissions reported in 2023 were on average 26 times higher than direct emissions (scopes 1 and 2). Yet only 15% of companies reporting to the CDP had set a reduction target on scope 3. In other words, the largest share of the footprint is also the least steered. The detail is in the CDP release "Scope 3 Upstream: Big Challenges, Simple Remedies".
Two approaches coexist to estimate a scope 3 emission. Physical data (kilos of material, kilometers, kilowatt-hours), multiplied by a precise emission factor. And monetary data (euros spent), multiplied by a monetary factor, less precise but quick to apply when physical data is missing. Companies often start with monetary data to map the categories, then refine the largest ones with physical data. The detail on factors is covered in our article on emission factors and the Base Empreinte.
How do you collect supplier data?
By engaging your suppliers, gradually, starting with those that matter most. You will not get primary data from all your suppliers on the first try, and that is not the goal. The right sequence:
- Map your purchases and spot the suppliers that concentrate most of your spend and your emissions.
- Start with a monetary estimate, from your purchase amounts and the factors of the ADEME Base Empreinte, to know where to act.
- Ask priority suppliers for the real data (product factor, footprint provided), and replace the estimate with this primary data.
- Expand year after year, bringing in more suppliers and categories.
Supplier engagement is not only a matter of collection: it changes the pathway. Again according to BCG and the CDP (June 2024), companies that engage their suppliers on climate are nearly 7 times more likely to have a scope 3 target and a 1.5°C-aligned transition plan. The data you ask for also pushes your suppliers to measure.
What share should you estimate when supplier data is missing?
You estimate, without stalling the footprint. A scope 3 is never 100% complete in primary data, and the GHG Protocol accepts this: you fill the gaps with secondary methods, then replace them over time with real data. The common methods:
- the monetary approach (spend-based): amount spent × monetary factor, useful to cover a broad scope quickly;
- sector averages or default data, when a physical factor exists for a type of product or service;
- extrapolation: applying the data of a representative supplier to comparable suppliers.
What matters is documenting the method chosen for each category and keeping it stable from one year to the next, so that your variations reflect real changes and not a change of calculation. An imperfect but transparent footprint beats a footprint delayed while waiting for perfect data that will never come.
Is scope 3 mandatory?
It depends on your situation. In the French regulatory footprint (the BEGES), scope 3 is mandatory only for companies subject to CSRD; other private companies are only required to report scopes 1 and 2. The detail is in our article on the mandatory carbon footprint (BEGES). For companies subject to CSRD, the ESRS E1 climate standard requires covering significant indirect emissions, scope 3 included. And beyond the obligation, most clients and rating frameworks ask for it.
Structure your scope 3 with Ditto
Scope 3 is where most of your footprint and most of the collection work lies. Ditto centralizes your purchasing, transport and travel data, applies emission factors, spots the significant categories and the missing data, and structures the engagement of your priority suppliers. A dedicated coach teaches you the method so you can run it yourself in the next cycle. And for a first scope 3, a platform like Ditto saves time, but a clear map of your purchases and a first spend-based calculation are already a solid place to begin.
Tackle your scope 3 with an expert
A Ditto expert reviews your significant categories, your supplier data and the calculation method with you.
Scope 3: key takeaways
| Item | Summary |
|---|---|
| Definition | Indirect emissions beyond purchased energy, upstream and downstream of the value chain |
| Categories | 15 in total: 8 upstream, 7 downstream (GHG Protocol) |
| Weight | Most often the largest share of the footprint; on average 26x scopes 1 and 2 (CDP/BCG, 2024) |
| Difficulty | Data outside the company; estimate in monetary terms then refine with physical data |
| Supplier data | Engage priority suppliers first, replace estimates with real data |
| Obligation | In the BEGES, scope 3 mandatory only if CSRD (ESRS E1); otherwise recommended |
Frequently asked questions
What are the 15 scope 3 categories?
The GHG Protocol defines 8 upstream categories (purchased goods and services, capital goods, fuel- and energy-related activities, upstream transportation and distribution, waste generated in operations, business travel, employee commuting, upstream leased assets) and 7 downstream categories (downstream transportation and distribution, processing of sold products, use of sold products, end-of-life treatment of sold products, downstream leased assets, franchises, investments).
Why is scope 3 hard to measure?
Because it depends on data you do not hold: emissions of your suppliers, your carriers, the use of your products. These third parties do not always measure them. You first fill the gaps with estimates (monetary approach, sector averages), then replace them with primary data on the categories that matter.
Do you have to report all 15 scope 3 categories?
No. The GHG Protocol asks you to cover the significant categories, those that matter most for your business. A services company focuses on travel and purchases of services, a manufacturing company on raw materials and use of sold products.
Is scope 3 included in the mandatory carbon footprint?
Only for companies subject to CSRD, which must cover their significant indirect emissions under the ESRS E1 standard. Other private companies are only required to report scopes 1 and 2 in the BEGES; scope 3 remains recommended there but not required.
