Estimate GHG Protocol Scope 3 emissions from your supply chain and value chain. Enter spend by category to calculate indirect CO2 using EEIO emission factors.
Scope 3 emissions encompass all indirect greenhouse gases in your value chain — from purchased goods and services to employee commuting to the end-of-life treatment of sold products. For most companies, Scope 3 is 5–20× larger than Scope 1 and 2 combined, yet it's the hardest to measure.
This Scope 3 Emissions Calculator uses the spend-based method, one of the most accessible approaches for initial estimation. Enter your annual spend in key categories (purchased goods, business travel, employee commuting, etc.) and the calculator applies Environmentally Extended Input-Output (EEIO) emission factors to estimate CO2.
While spend-based estimates are less precise than supplier-specific data, they provide a valuable starting point for identifying hotspots and prioritizing engagement with high-impact suppliers.
Integrating this calculation into regular energy reviews ensures that conservation strategies are grounded in measured data rather than assumptions about building performance and usage patterns. Precise measurement of this value supports sustainable energy planning and helps organizations reduce their environmental impact while maintaining operational performance and comfort levels.
Scope 3 is typically 80–95% of a company's total footprint. This calculator helps you make a first estimate, identify the biggest categories, and prioritize data collection and supplier engagement. Data-driven tracking enables proactive energy management, helping organizations reduce operational costs while progressing toward environmental sustainability goals and carbon reduction targets.
Scope 3 CO2 = Σ(Category Spend × EEIO Factor). EEIO factors vary by sector (kg CO2/$): Goods ~0.40, Travel ~0.30, Freight ~0.50, Commuting ~0.25.
Result: 2,725,000 kg CO2 (2,725 tonnes)
Goods: $5M × 0.40 = 2,000t. Travel: $500k × 0.30 = 150t. Freight: $1M × 0.50 = 500t. Commuting: $300k × 0.25 = 75t. Total: 2,725t.
Scope 3 is vast and complex. A consumer goods company's Scope 3 might include raw material extraction, manufacturing, packaging, global shipping, retail operations, consumer use, and end-of-life disposal. Each step involves different data sources and uncertainties.
The spend-based method is the fastest path to a Scope 3 estimate. It uses procurement data that most companies already have. While imprecise, it reveals which categories dominate and where to focus data improvement efforts.
Start with spend-based estimates, then progressively upgrade to hybrid and supplier-specific methods for the top categories. This iterative approach balances accuracy with practicality and builds organizational capability over time.
The GHG Protocol defines 15 categories: 8 upstream (purchased goods, capital goods, fuel/energy, transport, waste, business travel, commuting, leased assets) and 7 downstream (transport, processing, use of products, end-of-life, leased assets, franchises, investments). Sharing these results with team members or stakeholders promotes alignment and supports more informed decision-making across the organization.
Environmentally Extended Input-Output factors link dollars of spend in economic sectors to CO2 emissions. They come from national economic and environmental accounts (e.g., USEEIO). They're less precise than supplier data but widely available.
Spend-based estimates can be off by 30–50% for individual categories. However, they're useful for identifying hotspots. Over time, replace spend estimates with supplier-specific data for your largest categories to improve accuracy.
Scope 3 reporting is required by SBTi for companies setting science-based targets. The SEC rules and EU CSRD also require certain Scope 3 disclosures. Even without mandates, investors and customers increasingly request it.
Engage with top suppliers to set their own reduction targets. Switch to lower-carbon materials. Optimize logistics routes. Reduce business travel. Design products for longer life and recyclability. These actions often reduce costs too.
For initial screening and target-setting, yes. For formal SBTi submission, you'll need a more detailed inventory using the GHG Protocol Scope 3 standard and sector-specific guidance. This calculator helps you get started.