Scope 3 emissions are the hardest emissions for a company to count, because they happen outside the company's direct control — in the supply chain, during product use, and after disposal.

You already know that Scope 1 covers what a company burns directly, and Scope 2 covers the electricity it buys. Scope 3 is everything else: the emissions from a supplier's factory, the emissions when a customer uses a product, the emissions from shipping, from business travel on airlines you don't own, from waste in a landfill. If the company didn't directly operate the equipment or own the power line, but the emission happened because of something the company did, it usually lands in Scope 3.

The reason companies bother to measure Scope 3 at all is that for most businesses, it is the largest number. A clothing retailer's Scope 1 and 2 might be tiny — a few stores, some trucks — but Scope 3 includes every factory that made every shirt, every shipping container, every washing machine a customer will use to clean those shirts. For a software company, Scope 3 might be 99 percent of the total. Ignoring it means ignoring where the real impact is.

Key Takeaways

  • Scope 3 includes emissions from suppliers, customers, shipping, waste, and anything else the company didn't directly cause but wouldn't happen without the company's business.
  • Scope 3 is usually the largest of the three scopes for most companies, which is why investors and regulators push companies to measure it.
  • Companies often estimate Scope 3 using industry averages and spending data, because they rarely have direct access to every supplier's emissions numbers.
  • The Greenhouse Gas Protocol divides Scope 3 into 15 categories so companies can focus on the ones that matter most to their business.

The 15 categories of Scope 3

The Greenhouse Gas Protocol — the standard most companies use — breaks Scope 3 into 15 categories. A company doesn't have to measure all 15; it picks the ones that are material, meaning the ones that actually matter to its business and its emissions footprint.

The first eight categories happen before the company sells the product: purchased goods and services (the stuff suppliers make), capital goods (the factory equipment the company buys), fuel and energy-related activities (emissions from mining the coal or drilling the oil that powers the company), upstream transportation (shipping from suppliers to the company), waste generated in operations, business travel, employee commuting, and leased assets the company doesn't own. The next seven happen after: downstream transportation (shipping to customers), processing of sold products, use of sold products, end-of-life treatment of sold products, downstream leased assets, franchises, and investments.

For a car manufacturer, "use of sold products" is enormous — it's every mile every car will drive. For a software company, it might be zero. For a fast-fashion retailer, "end-of-life treatment" (what happens when customers throw clothes away) matters. For a consulting firm, it might not. The company's job is to figure out which categories move the needle and measure those.

How companies actually measure Scope 3

A company rarely has direct access to every supplier's emissions data. So it estimates. The most common method is to take the amount of money the company spent on a category — say, $10 million on raw materials — and multiply it by an industry average emissions factor. That factor comes from databases like the U.S. Environmental Protection Agency's supply chain database or Exiobase, which estimate how many tons of carbon are typically emitted per dollar spent in different industries.

For categories where the company has more control, it can be more precise. If the company owns the data on how many tons of product it shipped and what distance, it can calculate shipping emissions directly. If it tracks employee flights, it can use actual flight data. But for purchased goods from hundreds of suppliers in different countries, the company is working from averages.

This is why Scope 3 numbers vary so much between companies and why they change year to year — not always because the company's actual impact changed, but because the estimation method improved or the industry factors were updated. A company might report that Scope 3 dropped 15 percent, when really the database it uses just got better at measuring.

Why investors and regulators care about Scope 3

Investors care because Scope 3 often reveals where a company's real climate risk is. A company might have cut its own emissions to zero, but if its suppliers are coal-heavy or its product is energy-intensive to use, the company hasn't actually solved the problem — it's just moved it off its own balance sheet. Regulators care for the same reason: they want to know the true footprint, not just the convenient one.

Some regulations now require companies to report Scope 3. The Securities and Exchange Commission's climate disclosure rules, which explore to large U.S. public companies, require Scope 1 and 2 reporting and, for some companies, Scope 3 as well. The European Union's Corporate Sustainability Reporting Directive requires large companies to report all three scopes. These rules exist because without Scope 3, a company's emissions report is incomplete.

The difference between Scope 3 and carbon offsets

Scope 3 is a measurement. A carbon offset is a claim that emissions were prevented or removed somewhere else. They are not the same thing, and companies sometimes confuse them on purpose.

A company might report: "We measured our Scope 3 emissions at 100,000 tons. We bought offsets for 50,000 tons, so our net emissions are 50,000 tons." What actually happened is the company measured 100,000 tons and paid someone else to supposedly prevent or remove 50,000 tons somewhere else. The 100,000 tons still happened. The offset is a financial transaction, not a physical reduction. This matters because offsets are often cheaper than actually cutting emissions, so companies have an incentive to buy them instead of changing their supply chain or product design.

Scope 3 reporting forces the company to at least count what it's responsible for. Whether the company then reduces it or offsets it is a separate decision.

Why Scope 3 is harder to reduce than Scope 1 or 2

A company can switch to renewable electricity and cut Scope 2 in a few years. It can replace its delivery trucks with electric ones and cut Scope 1. But Scope 3 requires changing other people's behavior: convincing suppliers to use cleaner methods, designing products that use less energy when customers use them, or asking customers to change how they use the product.

A clothing company can ask suppliers to use renewable energy, but it can't force them. A car company can make cars more efficient, but it can't control how far customers drive. A software company can reduce the energy intensity of its data centers, but it can't control how much electricity the customer's device uses to run the software. This is why many companies report Scope 3 numbers but make smaller commitments to reduce them than they do for Scope 1 and 2.

How to read a company's Scope 3 report

When a company publishes its emissions, look for three things. First, which Scope 3 categories did it measure? If it only measured a few, it might be leaving out the big ones. Second, what method did it use? If it says "industry average spending-based estimate," it's using the multiplication method described above. If it says "supplier-specific data," it has better information. Third, what's the year-over-year change? A sudden drop might mean the company actually reduced emissions, or it might mean the estimation method changed.

You can also compare the company's Scope 3 to its Scope 1 and 2. If Scope 3 is 90 percent of the total, that's normal for most industries and means the company's real impact is in the supply chain or product use. If Scope 3 is only 10 percent, either the company's business is unusual or it's not measuring carefully.

Frequently Asked Questions

Is Scope 3 the same as indirect emissions?

Scope 2 is also indirect — the company doesn't burn the fuel, but it buys the electricity. The difference is that Scope 2 is indirect emissions from energy the company purchased, while Scope 3 is everything else indirect. Think of it this way: Scope 2 is the power line. Scope 3 is everything else outside the company's fence.

Can a company have zero Scope 3 emissions?

Only if the company does nothing — no supply chain, no customers, no products. Any real business has Scope 3. A company can reduce it significantly by redesigning products, switching suppliers, or changing how customers use the product, but zero is not realistic for most industries.

Why do different companies report different Scope 3 numbers for the same industry?

Because they measure different categories, use different estimation methods, and have different supply chains. One company might include business travel in Scope 3; another might count it in Scope 1. One might use supplier-specific data; another uses industry averages. These choices make the numbers hard to compare directly.

Does Scope 3 include emissions from recycling?

Yes, under the "end-of-life treatment of sold products" category. This includes the emissions from transporting waste to a recycling facility, running the facility, and processing the material. It's part of why some companies are starting to design products that are easier to recycle.

If a company offsets its Scope 3 emissions, does that mean it's carbon neutral?

Not necessarily. An offset is a claim that emissions were prevented or removed elsewhere, but the company's actual Scope 3 emissions still happened. Carbon neutral means the company measured its emissions and either reduced them to zero or bought offsets for all of them. But the offsets themselves vary widely in quality and certainty, so "carbon neutral" can mean very different things depending on which offsets the company bought.