1 · What Is Scope 3
What Are Scope 3 Emissions?
The GHG Protocol Corporate Accounting and Reporting Standard divides greenhouse gas emissions into three scopes based on how directly they relate to your operations:
- Scope 1: Direct emissions from sources you own or control — company vehicles, on-site combustion, refrigerant leaks
- Scope 2: Indirect emissions from purchased electricity, heat, or steam
- Scope 3: All other indirect emissions across your entire value chain — both upstream (suppliers) and downstream (customers, end-of-life)
Scope 3 is sometimes called "value chain emissions" because it encompasses everything that happens before and after your company's own operations. For most companies, it's by far the largest share of their total carbon footprint — often 65–90% of total emissions.
Why Scope 3 matters now
California SB 253 requires Scope 3 disclosure for companies with $1B+ revenue starting with FY2026 data. CSRD requires full Scope 3 for EU-covered companies. The SEC's Scope 3 requirement is currently stayed but applies to companies with net-zero targets. Enterprise buyers are also requesting Scope 3 data from suppliers as a procurement condition.
2 · Why It's Difficult
Why Scope 3 Is the Hardest Emissions Category to Measure
Scope 1 and Scope 2 are relatively straightforward — you look at your fuel bills and electricity invoices, apply standard emission factors, and you're done. Scope 3 is harder for three reasons:
1. The data doesn't live with you
Scope 3 emissions happen in your suppliers' facilities, in your employees' cars on the way to work, and in customers' hands when they use your products. You can't measure this directly — you have to estimate, request supplier data, or use economic models.
2. There are 15 distinct categories
The GHG Protocol defines 15 Scope 3 categories, split between upstream activities (what goes into your operations) and downstream activities (what happens after your product leaves). Each category requires different data and different calculation methods.
3. The boundary is fuzzy
Where does your company end and your supply chain begin? Companies often struggle to define the boundaries of what counts as Scope 3, leading to inconsistent reporting. The GHG Protocol provides guidance, but judgment calls are unavoidable.
⚠️ The good news: you don't need perfect data
Regulators and auditors expect progressive improvement. A well-documented first estimate using the spend-based method is far better than no estimate. Start with your top 3 emission categories, then improve accuracy over time.
3 · The 15 Categories
All 15 Scope 3 Categories (With Examples)
The GHG Protocol divides Scope 3 into upstream categories (1–8) and downstream categories (9–15). Not all categories are material for every company — a software company's profile looks very different from a manufacturer's.
Upstream Categories
Cat. 1
Purchased Goods & Services
Extraction, production, and transport of goods and services you purchase. Typically the largest Scope 3 category for most companies.
Example: A retail company's product manufacturers emit CO₂ producing the goods sold in-store
Cat. 2
Capital Goods
Emissions from the production of capital goods — equipment, buildings, vehicles — that you purchase.
Example: A logistics company buying 20 new trucks; the steel and manufacturing emissions are Scope 3 Cat. 2
Cat. 3
Fuel & Energy-Related Activities
Upstream emissions from extraction and production of fuels and energy not covered in Scope 1 or 2.
Example: The extraction and refining of gasoline before it reaches your fleet vehicles
Cat. 4
Upstream Transportation & Distribution
Emissions from transporting purchased goods to your operations — freight, rail, ocean shipping.
Example: Container shipping costs to bring inventory from overseas suppliers
Cat. 5
Waste Generated in Operations
Disposal and treatment of waste generated at your facilities — landfill, incineration, recycling.
Example: Office food waste sent to landfill; manufacturing scrap metal processed off-site
Cat. 6
Business Travel
Flights, hotel stays, car rentals, rail travel by employees for business purposes.
Example: Sales team flying 200 round trips/year; conferences attended by staff
Cat. 7
Employee Commuting
Emissions from employees traveling between home and work — personal cars, public transit, cycling.
Example: 500 employees averaging 25 miles/day by personal car
Cat. 8
Upstream Leased Assets
Emissions from operations of assets leased by your company and not in Scope 1/2.
Example: Leased warehouse operated by a third party on your behalf
Downstream Categories
Cat. 9
Downstream Transportation & Distribution
Emissions from transporting and distributing sold products to end customers.
Example: Last-mile delivery of e-commerce orders to consumers
Cat. 10
Processing of Sold Products
Emissions from processing intermediate products sold to downstream manufacturers.
Example: A chemical supplier's product being processed into a finished good
Cat. 11
Use of Sold Products
Emissions from the use of goods and services sold to customers — electricity consumption, fuel burned, etc.
Example: A power tool manufacturer's products consuming electricity over their lifetime
Cat. 12
End-of-Life Treatment of Sold Products
Emissions from waste disposal of your products after customers are done with them.
Example: A packaging company's containers ending up in landfill or recycled
Cat. 13
Downstream Leased Assets
Emissions from operation of assets you own and lease to others.
Example: A real estate company leasing office space to tenants
Cat. 14
Franchises
Emissions from franchisee operations — relevant for franchise businesses.
Example: A restaurant franchisor's 500 franchise locations' energy use
Cat. 15
Investments
Emissions from a company's equity and debt investments — primarily for financial institutions.
Example: A bank's loan portfolio's financed emissions
Which categories are most material for you?
For most mid-market companies: Cat. 1 (purchased goods), Cat. 6 (business travel), and Cat. 7 (employee commuting) account for 70–80% of Scope 3 emissions. Start there. Regulators accept a materiality-based approach in Year 1.
4 · Calculation Methods
Scope 3 Calculation Methodologies: Which One to Use
The GHG Protocol accepts several methodologies for calculating Scope 3 emissions. Each involves a tradeoff between data availability and accuracy. You don't have to pick one — most companies use a hybrid approach.
⬤ Easiest to implement
Spend-Based Method
Multiply supplier spend by economic input-output (EIO) emission factors. Uses publicly available data — your AP system is all you need.
Data needed: Spend by supplier category (from ERP/AP)
Accuracy: ±50% — sufficient for Year 1 baseline
Best for: Categories 1, 2, 4 when supplier data unavailable
Source: EPA EEIO-LCA emission factors or EXIOBASE
⬤ Moderate effort
Activity-Based Method
Multiply activity data (miles traveled, kg waste, kWh consumed) by specific emission factors. More accurate than spend-based.
Data needed: Activity quantities (flight miles, kg waste, etc.)
Accuracy: ±20–30% — good for reporting
Best for: Categories 6, 7 (travel/commuting), 5 (waste)
Source: EPA emission factors, ICAO for flights
⬤ Moderate effort
Average Data Method
Use industry-average emission intensity factors per unit of product or service purchased.
Data needed: Units purchased (tonnes, liters, kWh)
Accuracy: ±30–40%
Best for: Cat. 1 when spend data isn't available by category
Source: Industry databases, Ecoinvent, SimaPro
⬤ High effort, highest accuracy
Supplier-Specific Method
Request actual emissions data directly from suppliers via CDP questionnaires or direct data sharing agreements.
Data needed: Supplier-reported GHG data per unit
Accuracy: ±10% — required for CSRD
Best for: Top 10–20 suppliers by spend; required for CSRD
Source: CDP Supply Chain, direct supplier surveys
GHG Protocol recommended approach: Hybrid
Start with the spend-based method for all categories to establish a baseline. Then improve accuracy for your top 3–5 material categories by switching to activity-based or supplier-specific data. This is the approach auditors expect and regulators accept.
5 · Worked Examples
Practical Examples: Calculating Scope 3 by Source
Example 1: Business Travel (Category 6)
A 300-person professional services firm wants to calculate its business travel emissions. Their travel manager pulls spend from Concur for the fiscal year.
Activity-Based Calculation — 300-Person Firm
Business Travel Emissions Breakdown
Domestic air (150 trips × 800 mi avg round-trip)120,000 miles
Emission factor (domestic short-haul, EPA)0.156 kg CO₂e / mi
Domestic air emissions18.7 tCO₂e
International air (40 trips × 10,000 mi avg)400,000 miles
Emission factor (long-haul, with RFI)0.195 kg CO₂e / mi
International air emissions78.0 tCO₂e
Hotel stays (2,400 nights × 20 kg CO₂e/night)48.0 tCO₂e
Ground transport (rental cars, taxis, trains)12.4 tCO₂e
Total Business Travel (Cat. 6)157.1 tCO₂e/year
Example 2: Employee Commuting (Category 7)
The same firm has 300 employees averaging 22 miles each way to the office 3 days per week. They use the average-data method with EPA commuting factors.
Average-Data Calculation — 300-Person Firm
Employee Commuting Emissions
Employees300
Average commute distance (one-way)22 miles
Days in-office per year (3 days/wk × 48 wks)144 days
Total vehicle miles traveled1,900,800 miles
Mode split: 72% personal car, 18% transit, 10% other—
Car emissions (1,368,576 mi × 0.411 kg CO₂e/mi)562.4 tCO₂e
Transit emissions (342,144 mi × 0.089 kg CO₂e/mi)30.5 tCO₂e
Total Commuting (Cat. 7)592.9 tCO₂e/year
Commuting is usually bigger than travel
For knowledge-work companies, employee commuting (Cat. 7) is often 3–5× larger than business travel (Cat. 6). Hybrid work policies that reduce in-office days are one of the fastest ways to cut Scope 3 emissions for office-based companies.
Example 3: Purchased Goods — Spend-Based Method (Category 1)
A mid-size manufacturer wants to estimate their supply chain emissions without collecting data from every supplier. They use the spend-based method with EPA EEIO emission factors.
Spend-Based Calculation — Manufacturing Company
Purchased Goods & Services Emissions (Cat. 1)
Raw materials (metals, plastics) spend$8.4M × 0.42 kg CO₂e/$
Raw materials emissions3,528 tCO₂e
Contract manufacturing spend$12.1M × 0.31 kg CO₂e/$
Contract manufacturing emissions3,751 tCO₂e
Packaging materials spend$2.2M × 0.55 kg CO₂e/$
Packaging emissions1,210 tCO₂e
Other indirect spend (services, software)$3.8M × 0.18 kg CO₂e/$
Other indirect emissions684 tCO₂e
Total Purchased Goods (Cat. 1)9,173 tCO₂e/year
Try the free Scope 3 calculator
CarbonPilot calculates your Scope 3 emissions from business travel, employee commuting, and supply chain spend — using EPA 2024 emission factors — in under 5 minutes.
Calculate Your Scope 3 Emissions — Free →
6 · CarbonPilot
How CarbonPilot Automates Scope 3 Tracking
Manually calculating Scope 3 emissions is a spreadsheet nightmare. CarbonPilot automates the process end-to-end — from data collection to compliance-ready reporting.
What CarbonPilot calculates automatically
- Business travel (Cat. 6) — import travel data from Concur, TripActions, or upload a CSV; CarbonPilot applies EPA/ICAO factors by flight segment and hotel type
- Employee commuting (Cat. 7) — input headcount, average commute distance, and mode split; CarbonPilot applies regional transport emission factors
- Supply chain (Cat. 1) — enter procurement spend by category; CarbonPilot applies EEIO-LCA factors from EPA's supply chain database
- Fleet fuel (Scope 1) — enter annual fuel spend or gallons; CarbonPilot handles the conversion for gasoline, diesel, and natural gas
- Electricity (Scope 2) — enter electricity spend or kWh; CarbonPilot applies the correct EPA eGRID factor for your grid region
What you get
- Scope 1, 2, and 3 breakdown by source and category
- Downloadable PDF report formatted for SEC, CSRD, and California SB 253 disclosure
- Year-over-year tracking once data is saved (Professional plan)
- Regulatory deadline alerts and compliance roadmap
- Audit trail with methodology notes — exactly what third-party verifiers need
Free to start
The basic calculator is free — no account required. Enter your data, get your Scope 1/2/3 breakdown, and download a PDF. Professional plans add continuous monitoring, integrations, and regulatory alerts starting at $99/month.
7 · Regulatory Requirements
Where Scope 3 Reporting Is Required
| Regulation |
Who it covers |
Scope 3 required? |
Deadline |
| California SB 253 |
Public & private, $1B+ CA revenue |
Yes — all 15 categories |
FY2026 data due Jan 2027 |
| EU CSRD (ESRS E1) |
Large EU companies + non-EU with €150M+ EU revenue |
Yes — full Scope 3 with transition plan |
FY2025–2028 (phase-in) |
| SEC Climate Disclosure |
Large public companies (SEC registrants) |
Only if material OR included in climate targets |
Currently stayed pending litigation |
| UK TCFD |
Premium-listed UK companies, large AIM companies |
Encouraged, not mandatory for all |
Phased in 2022–2025 |
| Enterprise customer requirements |
Suppliers to Fortune 500 companies |
Increasingly yes — via CDP Supply Chain |
Ongoing; accelerating |
Even if none of the above mandates apply to you today, your largest customers are already asking for Scope 3 data. 73% of Fortune 500 companies have supply chain emission targets, and most are beginning to request actual data from key vendors rather than self-certification.
For a deeper dive into all regulatory requirements — SEC, CSRD, and California — see our full compliance guide.
Get your Scope 3 number in 5 minutes
CarbonPilot handles the math for fleet, travel, commuting, and supply chain spend. Free to use, no account required. Download a compliance-ready PDF when you're done.
Start Free Scope 3 Calculator →
8 · FAQ
Frequently Asked Questions
What's the difference between Scope 3 upstream and downstream emissions?
Upstream emissions (Categories 1–8) come from activities that go into your company's operations — the goods and services you purchase, the energy you use, and how your employees get to work. Downstream emissions (Categories 9–15) happen after your product or service leaves your company — transportation to customers, how customers use your product, and what happens at end-of-life. For most product companies, Categories 1 (purchased goods) and 11 (use of sold products) dominate. For service companies, Categories 6 (business travel) and 7 (employee commuting) are typically largest.
Do I need data from all 15 Scope 3 categories?
No. The GHG Protocol requires companies to report on all relevant categories, but "relevant" is defined by materiality. For most companies, 3–5 categories account for 80%+ of Scope 3 emissions. Start with your highest-spend procurement category (usually Cat. 1), employee commuting (Cat. 7), and business travel (Cat. 6). You can add categories over time as your reporting matures. Regulators and auditors expect a materiality-based approach in the first year or two.
Is the spend-based method accurate enough for compliance?
Yes for Year 1 — with appropriate caveats. The spend-based method has ±50% accuracy at the category level, which is acceptable for initial baseline reporting. California SB 253, CSRD, and most enterprise buyers accept spend-based estimates provided you document your methodology and emission factors clearly. The expectation is that you'll improve accuracy over time by switching to activity-based or supplier-specific data for your most material categories.
How do I get Scope 3 data from my suppliers?
There are two main channels. (1) CDP Supply Chain: if you're a CDP signatory, you can send emission data requests to your suppliers via the CDP platform — many large suppliers already respond. (2) Direct surveys: send questionnaires to your top 10–20 suppliers by spend asking for their product-level carbon intensity data. Expect a 40–60% response rate initially. For suppliers who don't respond, fall back to the spend-based or average-data method. The GHG Protocol Scope 3 Standard has templates for supplier engagement.
How does employee commuting get calculated?
The standard approach: (1) survey employees on their commute mode and distance, or (2) use an average for your company's location and industry. Then multiply by EPA emission factors for each transport mode. For example, a car commuter driving 20 miles each way, 240 days per year = 9,600 vehicle miles × 0.411 kg CO₂e/mile = 3.9 tCO₂e/year. CarbonPilot does this automatically — enter your headcount, average distance, and mode split. Hybrid/remote work policies that reduce in-office days directly reduce this number.
What emission factors should I use for Scope 3?
For US companies: EPA's Environmentally Extended Input-Output model (EEIO-LCA) for spend-based estimates; EPA AP-42 and eGRID for activity-based energy estimates; ICAO Carbon Emissions Calculator data for flights. For EU/global: EXIOBASE for spend-based; IPCC AR6 GWP factors for global warming potential conversions. CarbonPilot uses EPA 2024 emission factors across all categories. Always document which version of the emission factor database you used — this matters for year-over-year comparability.