Scope 3: How to Measure Your Indirect Emissions with the GHG Protocol

If you work in sustainability, Scope 3 isn't a new concept to you. And you know perfectly well the problem isn't understanding it. The problem is measuring it.

The data is scattered across departments with other priorities. Suppliers don't respond on time, or they respond with information you're not quite sure how to use. And every time you try to seriously get started, something more urgent shows up.

You've had that browser tab open for months and you can't keep saying "we're working on it." You need a result that holds up to an audit, a meeting with leadership, or a client requirement.

This guide exists for that moment.

This guide is for you if:

• You already measure Scope 1 and 2, but Scope 3 still isn't resolved
• You know which categories should apply to you, but aren't sure which one to start with
• You have some of the data, but it's scattered and unstructured
• You need to know how to calculate and defend your emissions figures
• CSRD, a client, or an audit is putting pressure on you

What you'll find in this guide:

• How to identify the categories that actually apply to you and rule out the rest
• When you can calculate without data from your suppliers (and when you have no choice but to ask them)
• The calculation formula for each category, no detours
• What to document so the result holds up to an audit
• A starter checklist to bring to your first internal meeting

If you want a quick overview first, check out the 15 categories of Scope 3 under the GHG Protocol or the definition of Scope 3 in our glossary.

When the problem stops being the calculation and becomes the system

Many teams manage to produce a first Scope 3 measurement. The problem shows up when they have to repeat it.

The following year, the data is scattered again. A client asks for the breakdown by category and you can't extract it. The audit needs traceability for every line and you have to dig through five different spreadsheets.

It's not the calculation that fails — it's the system.

At Manglai, we help sustainability teams turn that process into something that scales: centralizing data from multiple sources, automatic calculation with full traceability, supplier survey management, and audit-ready reports for CSRD or MITECO.

Without multiplying the effort every time you have to repeat it.

Download the free guide and start solving your Scope 3.