Scope 3 Emissions Calculator Formula
Understand the math behind the scope 3 emissions calculator. Each variable explained with a worked example.
Formulas Used
Total Scope 3 Emissions
total_out = total_scope3Purchased Goods Share
goods_pct = purchased_goods / total_scope3 * 100Travel & Commute Share
travel_pct = (business_travel + employee_commuting) / total_scope3 * 100Waste Share
waste_pct = waste_disposal / total_scope3 * 100Variables
| Variable | Description | Default |
|---|---|---|
purchased_goods | Purchased Goods & Services(metric tons CO2e) | 200 |
business_travel | Business Travel(metric tons CO2e) | 50 |
employee_commuting | Employee Commuting(metric tons CO2e) | 80 |
waste_disposal | Waste Disposal(metric tons CO2e) | 20 |
total_scope3 | Derived value= purchased_goods + business_travel + employee_commuting + waste_disposal | calculated |
How It Works
How to Calculate Scope 3 Emissions
Scope 3 covers all indirect emissions in your value chain not included in Scope 2. These are typically the largest portion of a company's total footprint.
15 Categories of Scope 3
Upstream: purchased goods/services, capital goods, fuel/energy activities, transportation, waste, business travel, employee commuting, leased assets.
Downstream: product transportation, processing, use of sold products, end-of-life treatment, leased assets, franchises, investments.
Formula
Total Scope 3 = Sum of all category emissions
Worked Example
A mid-size company with estimated Scope 3 across four main categories.
- 01Purchased goods: 200 metric tons CO2e
- 02Business travel: 50 metric tons CO2e
- 03Employee commuting: 80 metric tons CO2e
- 04Waste disposal: 20 metric tons CO2e
- 05Total Scope 3: 200 + 50 + 80 + 20 = 350 metric tons CO2e
Frequently Asked Questions
Why are Scope 3 emissions important?
Scope 3 often represents 70-90% of a company's total emissions. Ignoring them gives an incomplete and misleading picture of climate impact.
Are Scope 3 emissions hard to measure?
Yes, they require data from suppliers and customers. Many companies use spend-based estimates initially, then refine with supplier-specific data over time.
Are companies required to report Scope 3?
The EU CSRD, California SB 253, and SEC proposals include Scope 3. The GHG Protocol and SBTi also require Scope 3 when it exceeds 40% of total emissions.
Ready to run the numbers?
Open Scope 3 Emissions Calculator