
How DitchCarbon calculates Scope 3 emissions
Most Scope 3 calculations start with supplier surveys and spreadsheets. They're slow, patchy and hard to make auditable.
We work the other way round. We maintain a large dataset of company emissions disclosures, normalised to GHG Protocol categories. We match the organisations you buy from or invest in against that dataset, fall back to industry factors where a disclosure does not exist, and show you which is which. The result is numbers you can defend within 2 weeks, with every figure carrying its source and change history.
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. This page documents how the calculation behind that data works.
We will walk you through the methodology on live data and your own emission factors, with time for questions.

No supplier surveys needed to get started
Verified to ISO 14064-3, limited assurance, by UL Solutions
Numbers you can defend within 2 weeks
Entity resolution against DUNS, LEI and ISIN identifiers
Every figure carries its source and change history
The calculation, step by step
We build your Scope 3 footprint through six connected steps. Each step adds coverage, accuracy or consistency, and each one is documented below.
We collect company emissions data from public disclosures and reports submitted to us directly. Our extraction engine normalises units to kgCO2e and maps disclosed categories to GHG Protocol categories, and our analysts review anything the validation rules flag.
Where company data is missing, industry averages are used. Ensures full coverage across all suppliers.
We calculate emissions from spend, sector and activity, using an organisation's own disclosures where they exist and revenue-based factors where they do not.
We collect company emissions data from public disclosures and reports submitted to us directly. Our extraction engine normalises units to kgCO2e and maps disclosed categories to GHG Protocol categories, and our analysts review anything the validation rules flag.
We map organisations into parent and subsidiary relationships, then assign emissions to the correct legal entity. Data cascades down a corporate tree from parent to subsidiary, never upwards.
Where an organisation has not disclosed, we apply an industry average factor for its industry, region and year. Every result is labelled with the method behind it, so coverage gaps are shown, not hidden.
We match your records to a single company profile using DUNS, LEI, ISIN and other identifiers you hold. Duplicates and naming differences resolve to the same entity, so one organisation is counted once.
We calculate emissions from spend, sector and activity, using an organisation's own disclosures where they exist and revenue-based factors where they do not.
Every record carries its source document, a mirror copy on our servers, version history and the QA checks it passed. Estimates are replaced as better disclosures arrive.
The full methodology
Everything below is versioned and maintained as standards, data sources and coverage change. Every change is documented so earlier calculations stay reproducible.
Methodology version 2026.2. Last updated 28 July 2026.
Frequently asked questions
The questions procurement, sustainability and finance teams ask most often.
We use an organisation's own disclosed emissions data wherever it exists, matched to your records by entity resolution against DUNS, LEI and ISIN identifiers. Where an organisation has not disclosed, we apply a documented industry average factor for its industry, region and year, and label the result as such. You always see which method produced each number and where the underlying data came from.
Yes. The DitchCarbon Portal calculator is verified to ISO 14064-3, at limited assurance, by UL Solutions, and the verification is renewed annually. Every calculation carries its source, version history and change history, and you can export an evidence pack from the platform. DitchCarbon data has been used in emissions reports that were subsequently assured by ten different third-party assurance providers, including Big Four firms.
You get a documented industry average factor for that organisation in the meantime, labelled as an estimate, so your baseline is complete and honest rather than blank. From there you can send a targeted request through the platform, with guidance built in. We check public disclosures first, so we only ask for what is genuinely missing, and the estimate is replaced as soon as better data arrives.
We refresh organisation data and emission factors continuously, with documented sources. When a source updates, version control records the change and flags anomalies for review, and a restatement in a newer report overwrites the same year from an older one. You can see every version of a figure and what changed between them.
Yes. The platform shows where moving an organisation from a spend-based average to its own disclosed data would change your footprint most, so you can prioritise engagement by impact rather than by size. Coverage gaps are shown, not hidden, and your data quality position improves visibly as they close.
All five. Disclosed and assured emissions map to DQ 1, unverified disclosures to DQ 2, activity-based calculations to DQ 3, revenue-based modelling to DQ 4, and industry averages to DQ 5. Every figure is labelled with the method that produced it, so a portfolio's weighted average DQ score can be calculated and defended. See how the methods map to the PCAF scale in the emissions calculation section above, or read our guide to PCAF data quality scores.
See the methodology working on your own data
This page documents the calculation. A walkthrough shows it running against the organisations in your own supply chain or portfolio, with the source behind every figure.








