Scope 3: what it is, how to calculate it (and how to fund it)

"Is scope 3 really essential?" The question comes up often, especially when a business leader wants to shorten the engagement. In regulatory terms, everything depends on your status. For anyone carrying out a Bilan Carbone® to decarbonise, the answer is yes, because this is where most emissions lie.

A Bilan Carbone® without scope 3 leaves out most emissions, and with them the most powerful opportunities to decarbonise: purchases, transport, travel, end of life. The State has also broadened its own perspective: the SNBC 3 Decree of 16 July 2026 sets indicative targets for France's carbon footprint, including imported emissions.

1What exactly is scope 3?

Bilan Carbone® sorts your emissions into 3 compartments, the scopes. Scope 1 groups the emissions you produce yourself, on site: the gas boiler, fleet vehicles, leaking refrigerants. Scope 2 covers energy you buy from someone else, mainly electricity and district heating. Scope 3 includes everything else: what you buy, what you transport, how your employees get to the office, what happens to your products once sold. In short, your entire value chain.

Scope 3 attracts attention because it accounts for an average of 88% of a company's total emissions. Scopes 1 and 2 (the boiler, fleet, electricity) are the most visible and easiest to measure, but remain a minority in almost every sector.

2The 15 scope 3 categories

The GHG Protocol, the international framework, divides scope 3 into 15 categories, but in most companies, 3 or 4 of them explain 80% of the total. They fall into 2 groups: upstream (what you consume to keep the company running) and downstream (what happens once your product or service has left your premises).

The 8 upstream categories (what you consume)

The upstream categories cover everything that enters your company - from raw materials to your employees' journeys. These are generally the categories that contribute most to the assessment, and those where you have the most direct opportunities to act.

• Category 1 - Purchased goods and services: often the largest scope 3 category, sometimes more than 50% of the total footprint. Raw materials for a manufacturer, medicines and medical devices for a hospital, subcontracting and digital services (cloud, SaaS, AI) for services
• Category 2 - Capital goods: fixed assets (buildings, vehicles, machinery, servers), whose manufacturing footprint is amortised over their lifetime
• Category 3 - Upstream energy: extraction and transport of the fuels and electricity you consume, before they even reach you
• Category 4 - Upstream transport: freight carrying your purchases to your premises, where road freight dominates in France (80% of tonne-km). It contributes heavily in industry and commerce
• Category 5 - Waste: treatment of everything you discard, often underestimated in services (WEEE, paper, furniture)
• Category 6 - Business travel: plane, train and car for appointments, trade shows and conferences. This is the category that sparks the most debate in the executive committee, because it affects business leaders' habits
• Category 7 - Employee commuting: your employees' journeys, often a large category for service companies in areas poorly served by transport
• Category 8 - Upstream leased assets: rented premises, leased vehicles, meaning emissions from assets you do not own

The 7 downstream categories (what you sell)

The downstream categories cover what happens after your product or service has left your hands. In some sectors, they dwarf the rest of the footprint.

• Category 9 - Downstream transport: freight carrying your products to customers, particularly significant in e-commerce and physical distribution
• Category 10 - Processing: if your product is a component that someone else processes before selling it to the end customer
• Category 11 - Product use: the huge category for carmakers and manufacturers of energy-intensive equipment. For a carmaker, category 11 alone exceeds 80% of scope 3
• Category 12 - End of life: what happens to your product once discarded (recycling, landfill, incineration)
• Category 13 - Downstream leased assets: what you lease to others (property, equipment)
• Category 14 - Franchises: emissions from franchisees operating under your brand
• Category 15 - Investments: for banks and insurers, this is almost all of scope 3, with "financed emissions". This is why the financial sector's scope 3 reaches 99.98% of the total footprint

3How much scope 3 contributes in your sector

The share of scope 3 varies by a factor of 5 depending on the sector, and the breakdown rarely resembles what you imagine. In financial services, it reaches 99.98% of the footprint, because financed emissions dwarf everything else. In commerce and distribution, it accounts for 85 to 95% (purchased goods dominate), and 70 to 90% in manufacturing depending on supply chain complexity. In healthcare, it approaches 84%, with purchases of medicines and medical devices contributing heavily. In tech, it accounts for 70 to 85% (servers, equipment, travel). In cement or steelmaking, among the sectors with the most intensive direct emissions, it falls to 16-20%, while remaining enormous in absolute terms.

In every case, scope 3 remains the boundary for strategic opportunities. Even when it accounts for only 50% of the footprint, this is where far-reaching choices are made: suppliers, product design, distribution model. Scopes 1 and 2 concern operational optimisation (switching to LEDs, replacing a boiler, renovating a building); scope 3 concerns business strategy. Measuring scope 3 also saves time: you stop exhausting yourself on 2% opportunities and work where the volumes lie.

4How to calculate scope 3 without spending 6 months on it

You do not need to know everything to start: nobody calculates scope 3 supplier by supplier in the first year. There are 3 methods, from the fastest to the most precise, and they are combined.

The spend-based approach: the entry route

Take spending by purchase category from your management accounts and apply the ADEME Base Empreinte ratios, in kgCO2e per €k spent: €200k of IT services immediately gives an order of magnitude. The method is quick and sufficient to identify the main categories and launch an action plan. Watch the versions: the ratios were recalibrated in March 2025 using the FIGARO MRIO model. For pharmaceuticals, for example, the factor fell from 1,600 to 603 kgCO2e/€k, and an assessment using the old ratios can overestimate some categories by a factor of 2.5. Check that your provider uses up-to-date factors.

The hybrid approach: the one we recommend

This is the approach that gives the best results for management: spend-based ratios for most purchases, physical data for the 3 to 5 categories contributing most. If your raw material purchases account for 40% of the footprint, it is worth asking the main supplier for its footprint per tonne. If travel is a major category, an internal mobility survey will be more reliable than a sector ratio. The aim is to reach the granularity needed to choose the right opportunities, without seeking perfect precision. This is the approach we use in most of our engagements.

Supplier data, for later

Ask each significant supplier for its precise carbon footprint: this is ideal for year-on-year monitoring and committing to an SBTi pathway. In practice, most suppliers have not yet carried out their own Bilan Carbone®. The data they provide are sometimes less reliable than a good sector ratio. Supplier engagement is 12 to 24 months of work - it is part of the reduction strategy, rather than the first measurement. Do not hold up your first assessment waiting for data that do not yet exist.

5Where to start, and with what grants

Diag Décarbon'Action, still widely underused, funds 40% of an initial Bilan Carbone®. Run by ADEME and Bpifrance, it is open to companies with fewer than 500 employees that have been operating for at least 1 year and have not carried out a GHG assessment in the past 5 years. It includes a complete Bilan Carbone® (scopes 1, 2 and 3) and a quantified, prioritised action plan, carried out by an ABC-certified consultancy. The service costs €10,000 excl. VAT, with €4,000 covered by the grant, leaving €6,000 excl. VAT payable by the company: for an SME, this is the most accessible entry route.

A complete engagement (scopes 1, 2 and 3 and an action plan) generally takes between 3 and 5 months: one month of scoping and data collection, one month of calculation, one month of analysis and action planning. On the company side, allow 1 to 2 person-days per month during the engagement, with most of the work handled by the consultancy: the project runs alongside normal business activity.

Why do it even without a direct requirement

If you are an SME with fewer than 500 employees, scope 3 is not directly mandatory for you, but your clients increasingly request it. Large companies subject to CSRD, refocused by the Omnibus I Directive on those with more than 1,000 employees and more than €450 million in turnover, must document their scope 3, meaning value chain emissions, of which your company is part. From the 2027 financial years, once Omnibus has been transposed, their requests to suppliers with at most 1,000 employees will be capped at the content of the voluntary standard derived from VSME, which includes greenhouse gas emissions. For public procurement, since 22 August 2026, each new tender procedure includes at least one environmental award criterion and an environmental contract performance clause. No Bilan Carbone® is required, but it helps justify the performance you claim.

The right order of steps

The process follows a logical sequence of 4 stages, and each feeds the next. Scoping is quick: 2 to 3 weeks to define the boundaries, reference year and expected level of detail. Collection is the most demanding phase for the company: gathering energy bills, purchase management accounts, the vehicle inventory and mobility survey. It is also the phase that reveals most about the organisation.

• Scoping: boundaries, reference year, identifying internal contributors (2 to 3 weeks)
• Collection: energy bills, purchase accounts, vehicle inventory, mobility survey (1 to 2 months)
• Calculation: applying emission factors, combining spend-based ratios and physical data (2 to 3 weeks)
• Presentation and action plan: presentation to the executive committee, ranking opportunities by impact and feasibility, quantifying expected reductions (2 to 3 weeks)

6Key takeaways

Scope 3 accounts for an average of 88% of a company's emissions, and therefore most reduction opportunities: leaving it out means managing your climate strategy with 12% of the data. 4 ideas to keep in mind before starting.

• Scope 3 accounts for an average of 88% of emissions, and up to 99% in financial services. It dominates everywhere except very energy-intensive industries (cement, steelmaking), where it falls to 16-20%
• Purchases account for 40 to 70% of scope 3 and are the first category to map: raw materials, subcontracting, services. This is where carbon strategy meets procurement strategy
• BEGES requires scope 3 for the public sector and companies subject to CSRD, now refocused on the largest, and recommends it for others. Since 22 August 2026, new public tender procedures also include an environmental criterion
• Start with quick wins: identify 3 to 5 priority categories and find a short-term opportunity in each. This is how the process earns internal credibility, far more than by displaying a 2050 pathway

Scope 3 is the most expensive and slowest part of an assessment, but also the part that informs important decisions: sourcing, product design, travel policy, distribution model. A company measuring it now, even imperfectly, will be a year ahead of those waiting until they are compelled to do so.

Further resources

Frequently asked questions

1What is Bilan Carbone® scope 3, in one sentence?

Scope 3 is all your indirect emissions excluding energy: purchases, freight, travel, use of sold products, end of life. On average, 88% of your total footprint. It is the boundary containing both the real volumes and the real reduction opportunities.

2Is scope 3 mandatory for SMEs?

Not directly if you have fewer than 500 employees, but your large clients subject to CSRD request your carbon data for their own scope 3, within the limits of the voluntary standard derived from VSME from the 2027 financial years, once Omnibus has been transposed, if you have at most 1,000 employees. Since 22 August 2026, new public tender procedures also include an environmental criterion. Having measured scope 3 becomes a commercial advantage.

3How do you calculate scope 3 when suppliers do not have their data?

Use the ADEME Base Empreinte spend-based ratios (updated in March 2025 using the FIGARO model): take spending by supplier category and apply the ratio, in kgCO2e per €k. This is enough to identify the main categories and start. Then refine it using physical data for the 3 to 5 dominant categories.

4How much does scope 3 cost?

Scope 3 is part of the complete Bilan Carbone®. For an SME, allow €10,000 to €30,000 excl. VAT depending on complexity, including everything (scopes 1, 2, 3 + action plan). With Diag Décarbon'Action, the cost payable by the company falls to €6,000 excl. VAT. An assessment covering only scopes 1 and 2 costs less but measures only 10 to 20% of your actual footprint.

5How long does a scope 3 Bilan Carbone® take?

Between 3 and 5 months for a single-site SME, including the consultancy. On the company side, allow 1 to 2 person-days per month during the engagement. The longest phase is data collection (purchases, mobility, energy). Calculation and analysis are quick once collection is sound.

6What are the 15 scope 3 categories?

The GHG Protocol divides scope 3 into 8 upstream categories (purchased goods and services, capital goods, upstream energy, upstream transport, waste, business travel, employee commuting, leased assets) and 7 downstream categories (downstream transport, processing, product use, end of life, downstream leased assets, franchises, investments). Category 1 (purchases) is almost always dominant.

7Is scope 3 mandatory in regulatory BEGES?

Not for all companies. Since 1 January 2023 (Decree No. 2022-982 of 1 July 2022), significant scope 3 indirect emissions have been mandatory for public-law legal entities and companies required to publish sustainability information, now in the sustainability report. Other companies subject to BEGES may limit themselves to scopes 1 and 2, provided they explain in the report how scope 3 has been addressed. They then leave out most of their footprint: scope 3 accounts for an average of 88% of a company's emissions.

8What are the most common scope 3 hotspots by sector?

Purchased goods and services (category 1) almost always come first and account for 40 to 70% of scope 3. The rest depends on the sector: use of sold products (category 11) exceeds 80% of a carmaker's scope 3, investments (category 15) make up most of banks' and insurers' footprints, downstream transport contributes heavily in e-commerce and distribution, and medicines contribute massively to a healthcare establishment's footprint. In most companies, 3 or 4 categories out of 15 explain 80% of the total, and these are where physical data should be collected first.

9Can scope 3 be reduced, or must it be accepted?

It can be reduced, and this is where the most powerful opportunities lie, provided they are treated as strategic decisions: choosing suppliers and materials, product design, travel policy, freight and distribution model. The method is to identify the 3 to 5 categories contributing most, find an initial short-term opportunity in each, then engage the main suppliers, a process taking 12 to 24 months. Their data then enable reductions to be tracked year after year, particularly as part of an SBTi pathway.

10What is the relationship between scope 3 and CSRD?

CSRD requires companies subject to it to publish their scope 1, 2 and 3 emissions annually in their sustainability report, under ESRS E1, with a reduction pathway. Since the Omnibus Directive entered into force on 18 March 2026, only companies with more than 1,000 employees and €450 million in turnover are concerned, with a first report in 2028 on the 2027 financial year. To document scope 3, they approach their suppliers, including SMEs not subject to the requirements, from whom they will not be able to request more than the voluntary standard derived from VSME if they have at most 1,000 employees, from the 2027 financial years and once Omnibus has been transposed.

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