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Carbon footprinting guide

A carbon footprint measures the total greenhouse gas emissions caused directly and indirectly by a person, organisation, event or product.

A carbon footprint is measured in tonnes of carbon dioxide equivalent (tCO2e). The carbon dioxide equivalent (CO2e) allows the different greenhouse gases to be compared on a like-for-like basis relative to one unit of CO2. CO2e is calculated by multiplying the emissions of each of the six greenhouse gases by its 100 year global warming potential (GWP).

A carbon footprint considers all six of the Kyoto Protocol greenhouse gases: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs) and Sulphur hexafluoride (SF6).

Types of carbon footprinting

The main types of carbon footprint for organisations are:


Emissions from all the activities across an organisation, including buildings' energy use, industrial processes and company vehicles.

Value chain 

Includes emissions which are outside an organisation's own operations (also known as Scope 3 emissions).  This represents emissions from both suppliers and consumers, including all use and end of life emissions.  


Emissions over the whole life of a product or service, from the extraction of raw materials and manufacturing right through to its use and final reuse, recycling or disposal.

Supply chain

Emissions from the raw materials and services that are purchased by an organisation in order to deliver its service(s) and/or product(s).


Carbon footprinting guide

Carbon footprinting

Published January 2018

Our 27-page guide to carbon footprinting explains what is included in organisational, supply chain and product footprints, how you can measure and communicate them, and the benefits of doing so. We also set out the specific steps you need to take to calculate your carbon footprint(s), and some of the key things to consider if you do.

Guide contents:

  • Introduction to carbon footprinting
  • Organisational carbon footprints
  • Why calculate your organisational carbon footprint?
  • Carbon Trust Footprinting services
  • The Carbon Trust Standard
  • How to calculate an organisational carbon footprint
  • Scope 2 reporting guidance
  • Setting a science-based carbon reduction target
  • Communicating your organisational carbon footprint
  • Product carbon footprint 
  • Why calculate your product carbon footprint?
  • How to assess your product carbon footprint
  • Communicating your product carbon footprint

Publication date: January 2018; Publication code: CTV043 v3

Information in this guide was correct at the time of publication

Download the guide:

Further information

Greenhouse gas conversion factors are used to calculate the amount of greenhouse gas emissions caused by energy use.  Our conversion factors guide contains these factors along with a spreadsheet to enter your usage and calculate carbon emissions.

For further support, find out more about our carbon footprinting services:

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