The calculator uses government-published emission factors wherever they exist and are able to use in the context of a free calculator and custom-built factors where they do not, for example, countries in the Global South.
Grid electricity uses each country's official or recognised national source (for example DESNZ, the EPA, the AIB or UBA). For the countries that don't publish one, it uses factors Equipoise builds from Ember generation data and IPCC values.
Fuels, vehicles, travel, freight, waste and water use the UK government's (DESNZ) conversion factors.
Spend-based emissions use EXIOBASE 3.8, adjusted to each reporting year's prices and converted at UN exchange rates.
Homeworking, air conditioning and commercial refrigeration use custom-built factors for every country, based on published papers and datasets that provide, for example, heating or air conditioning usage for each country.
Each result records which factor and version it used.