What is Scope 3 Category 1 (purchased goods and services)?

For companies that buy more than they make it is usually the largest reporting line, and it is the category that pulls a sustainability team into procurement data whether they planned for it or not.

What is inside the Category 1 boundary?

The boundary is cradle-to-gate: everything from raw material extraction to the point the good leaves the supplier, or the service is delivered. Four things that feel like they belong here sit elsewhere in the GHG Protocol:

• Capital goods go to Category 2. The test is how the item is accounted for, not what it is.
• Fuel and energy you purchase go to Scope 1, Scope 2 or Category 3, depending on the type.
• Transport you pay for goes to Category 4, not Category 1.
• Waste from your own operations goes to Category 5.

The boundary decides which category an invoice lands in, because the same supplier invoice can sit in Category 1 or Category 2 depending on how finance coded it.

What are the four ways to calculate Category 1?

The GHG Protocol Scope 3 Standard sets out four methods for this category.

• Supplier-specific method. Use cradle-to-gate data from the supplier itself, for the goods or services you bought. Highest accuracy, needs the supplier to have done the work.
• Hybrid method. Use supplier-specific data where you have it and fill the rest with secondary data. It is the method the Scope 3 Standard expects where supplier data is partial.
• Average-data method. Multiply the physical quantity purchased, by mass or unit, by a secondary emission factor for that material or product.
• Spend-based method. Multiply what you spent by a secondary emission factor per unit of spend for that sector and region.

Which method should you use?

The GHG Protocol asks for the most accurate method the available data supports, applied line by line rather than across the whole category. A mixed inventory is normal and expected: supplier-specific figures for the suppliers that matter and have disclosed, spend-based estimates for the long tail. What matters at review is that each line is labelled with the method behind it, so an assurance provider can see which parts of the total are measured and which are estimated.

Why does the spend-based method get criticised?

Because it cannot tell two suppliers apart. Every supplier in the same sector and region gets the same factor, so the best performing supplier in a category and the worst produce identical numbers, and a supplier that halves its emissions changes nothing in your report. Spend-based estimates are a legitimate starting point and a poor basis for a decision. A spend-based baseline is proxy data, and replacing it means spreadsheets and chasing suppliers.

How do you move off spend-based?

Start with what has already been published. Part of the long tail has a disclosure nobody has looked for, which converts a spend-based line into a reported one without asking the supplier for anything. Then ask, and ask narrowly, with the request prepopulated from whatever has been found. Prepopulated requests get higher response rates than a cold survey, because the supplier is confirming figures rather than filling an empty form.

A recent deployment reached about 60% of a large supplier base within 2 weeks, which is the shape of the curve when the published data is used first and the asking is targeted at what is left.

Where does DitchCarbon fit?

DitchCarbon provides verified emissions data for over 2 million organisations, so procurement, sustainability and finance teams can measure and act on supply chain and portfolio emissions from one source. For Category 1 that means each supplier arrives with a figure, the method behind it, and its source and change history, so the supplier-specific lines and the estimated lines sit in one total that adds up. Where a supplier has published nothing, the estimate uses documented industry factors and the gap is shown rather than hidden. That is what gets a team to numbers you can defend within 2 weeks.

From there the work is engagement: which suppliers to approach, what to ask each one for, and what changes in the total when they answer. See how the Scope 3 calculation works for the method in full.

Will an auditor accept a Category 1 total built this way?

That determination belongs to your assurance provider, and what they ask for is a trail. What you hand over is audit-ready and verified to ISO 14064-3, limited assurance, by UL Solutions, renewed annually. Every figure carries its source and change history, and the original disclosure is mirrored so the trail survives a supplier moving its report. The emission factor methodology was independently assessed by Globus Thenken, August 2025, and assessed as compliant with the GHG Protocol Scope 3 Standard and ISO 14064-1:2018. DitchCarbon is the only specialist Scope 3 tool with third-party assurance of its calculation methodology: the reports are on the trust centre, and the verification benchmark lists every vendor we checked, verified or not.

Related

• What is Scope 3 Category 2 (capital goods)?
• What is a spend-based emissions calculation?
• What is supplier-specific emissions data?
• What are upstream Scope 3 emissions?

Has a customer asked you for Category 1 data? Claim your company profile and answer once, so the next customer request starts from what you have already published. Or see the coverage on your own supplier list.

Last reviewed July 2026.