Scope 3 emissions are all indirect greenhouse gas emissions that occur across a company's value chain — both upstream (in the supply chain and from employee activities) and downstream (from how customers use and dispose of the company's products).
The GHG Protocol defines 15 distinct Scope 3 categories, ranging from purchased goods and services through to end-of-life treatment of sold products and emissions from investments.
Why it matters
For most businesses, Scope 3 is by far the largest part of the carbon footprint — often 70–90% of total emissions. It is also the area where procurement frameworks now demand more rigour. PPN 006, the NHS Net Zero Supplier Roadmap, and CDP all require Scope 3 reporting at increasing levels of detail.
Scope 3 is harder to measure than Scope 1 and 2 because the data sits outside the reporting company's direct control. This is where methodology choices matter most: activity-based data produces materially more accurate results than spend-based estimation.
A practical example
A drinks company's Scope 3 footprint will typically be dominated by purchased goods and services (Category 1) — glass bottles, cardboard packaging, agricultural ingredients — followed by upstream and downstream transport, employee commuting, business travel, and end-of-life packaging treatment. Together these often outweigh on-site fuel and electricity by an order of magnitude.
See how we screen, collect, and calculate every Scope 3 category on the methodology page.