SustainMetrics
FreemiumLiveLast verified 24 Sept 2026
18,000+ GHG emission factors from DEFRA, EPA, ADEME and Ember for Scope 1-3 carbon footprint calculations.
Example request
curl -s 'https://www.sustainmetrics.net/api/v1/factors?source=defra&year=2025&category=fuels' -H 'X-API-Key: $API_KEY'
Free tier, in plain English
Free API key gives 50 requests a day; the web calculator itself is free and keyless.
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