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Carbon dioxide equivalent (CO2e): definition and calculation

Carbon dioxide equivalent (CO2e) is the common unit that allows all greenhouse gases to be summed into a single measure of climate impact.

How it is calculated

Multiply the quantity of each gas by its global warming potential (GWP). For example, methane has a GWP of about 28 to 30 over 100 years: 1 kg of methane equals about 28 kg of CO2e.

Why it is useful

CO2e allows emissions of very different natures to be compared and summed into a single indicator. All UltraCarbon results are expressed in CO2e (kg or tonnes).

Frequently asked questions

CO2 or CO2e?

CO2 is a specific gas; CO2e aggregates all GHGs converted to the effect of CO2. A carbon assessment is expressed in CO2e.

What does tCO2e mean?

Tonnes of CO2 equivalent. It is the standard unit of a corporate carbon assessment.

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Carbon assessment: definition, method and obligations →ISO 14067: the carbon footprint of products →Understanding Scopes 1, 2 and 3 →CSRD: the European sustainability reporting directive →Emission factor: definition and sources →Life-cycle assessment (LCA): principles and method →SBTi: science-based climate targets →BEGES: the regulatory GHG emissions assessment (France) →GHG Protocol: the global carbon accounting framework →Carbon neutrality: definition, limits and best practices →Environmental labelling: what is changing for products →Decarbonisation plan: from measurement to action →Carbon offsetting: how it works, quality and limits →Digital carbon footprint: measure and reduce →CBAM: the carbon border adjustment mechanism →Industrial carbon assessment: challenges and method →Food industry carbon assessment: challenges and method →Textile and fashion carbon assessment: challenges and method →Construction carbon assessment: challenges and method →Transport and logistics carbon assessment: challenges and method →E-commerce carbon assessment: challenges and method →Tech, SaaS and startup carbon assessment: challenges and method →Hospitality and catering carbon assessment: challenges and method →Healthcare and hospital carbon assessment: challenges and method →Cosmetics carbon assessment: challenges and method →Wine and spirits carbon assessment: challenges and method →Banking and finance carbon assessment: challenges and method →Retail and distribution carbon assessment: challenges and method →Local authority carbon assessment: challenges and method →SME carbon assessment: where to start →Business travel: measuring and reducing the carbon footprint →Commuting: calculating and reducing the carbon footprint →Business energy: electricity, gas and carbon footprint →Tertiary buildings: carbon footprint and energy regulations →Waste management: carbon footprint and reduction →Responsible purchasing: reducing upstream Scope 3 →Event carbon assessment: method and reduction →Carbon accounting software: how to choose well →Cost of a carbon assessment: how much does it cost? →Doing your carbon assessment yourself or with a consultancy? →How to calculate Scope 3: a practical guide →How to collect data for a carbon assessment →How to reduce your company's carbon footprint →How to prepare for the CSRD: key steps →ISO 14064: the standard for quantifying greenhouse gases →The Bilan Carbone® method: origin and principles →FDES and EPD: product environmental declarations →PEF: the European Product Environmental Footprint →CDP: climate reporting for investors →EcoVadis: CSR assessment of suppliers →Double materiality: definition and method →EU green taxonomy: principles and criteria →Green Claims Directive: regulating environmental claims →Duty of due diligence (CSDDD): what to know →SNBC: France's national low-carbon strategy →The 15 Scope 3 categories explained →Scope 2: market-based or location-based? →Base Empreinte (ADEME): the emission factor database →Greenhouse gases: CO2, methane and CO2e →The Paris Agreement and the 1.5°C target →TCFD: climate risks and financial reporting →GRI and SASB: sustainability reporting standards →Eco-design: reducing impact from the design stage →Carbon budget: definition and purpose →Net Zero: definition and difference from carbon neutrality →Carbon credit: definition and how it works →The Low-Carbon Label: financing projects in France →Carbon market and EU ETS: the European allowance system →Carbon pricing: tax, market and internal price →Greenwashing: definition and how to avoid it →The IPCC: role and climate reports →Global warming: causes and consequences →The ACT method: assessing climate strategy alignment →Carbon footprint: definition and calculation →Key climate and emissions figures →Carbon assessment glossary: the essential terms →