Carbon Footprint Calculator for UK SMEs

A business carbon footprint is the total amount of greenhouse gas emissions produced directly and indirectly by a company, measured in tonnes of carbon dioxide equivalent (CO2e). It covers Scope 1 emissions from owned sources like company vehicles and gas heating, Scope 2 from purchased electricity, and Scope 3 from indirect activities like business travel, commuting and supply chain.

Most UK SMEs are not legally required to report carbon emissions under the Streamlined Energy and Carbon Reporting (SECR) regulations, which apply to large companies and quoted companies. However, many SMEs voluntarily measure and report their footprint for tender requirements, customer expectations, B Corp certification, or as part of larger supply chains. The UK government encourages voluntary disclosure through schemes like the SME Climate Hub.

Scope 1 covers direct emissions from sources the company owns or controls, such as company vehicles, on-site gas boilers and refrigerant leaks. Scope 2 covers indirect emissions from purchased electricity and heat. Scope 3 is the broadest category, covering all other indirect emissions including business travel, employee commuting, purchased goods, waste disposal and downstream use of products. For most SMEs, Scope 3 is the largest category.

The UK Government publishes annual greenhouse gas conversion factors. For 2025, the electricity emission factor is approximately 0.207 kg CO2e per kWh. This reflects the UK grid mix including renewable, nuclear and fossil fuel generation. The factor has been declining year on year as more renewable capacity comes online. Natural gas is approximately 0.183 kg CO2e per kWh.

The most impactful steps for UK SMEs include switching to a 100% renewable electricity tariff, improving building insulation and heating efficiency, transitioning company vehicles to electric, reducing business flights by using video conferencing, encouraging remote working, reducing waste and recycling more, and choosing lower-carbon suppliers. Setting science-based targets through the SBTi gives a structured reduction pathway.

CO2e stands for carbon dioxide equivalent. It is a standard unit that expresses the global warming potential of different greenhouse gases in terms of the amount of CO2 that would create the same warming effect. For example, methane is roughly 28 times more potent than CO2 over 100 years, so 1 tonne of methane equals 28 tonnes CO2e. This allows all emissions to be compared on a single scale.

UK SME emissions vary enormously by sector and size. A typical office-based business with 10-20 employees might emit 15-40 tonnes CO2e per year. Construction and manufacturing SMEs tend to be higher at 50-200 tonnes. Retail businesses fall in between. The UK average is approximately 3-5 tonnes CO2e per employee per year across all sectors, but this is a rough guide only.

Multiply the total annual mileage by the appropriate emission factor for the vehicle type. Petrol cars emit approximately 0.17 kg CO2e per kilometre and diesel cars approximately 0.18 kg CO2e per kilometre. For more accurate figures, use the specific DEFRA conversion factor for your vehicle size and fuel type. Electric vehicles have zero Scope 1 emissions but the electricity used to charge them counts as Scope 2.

Business flights are a significant source of emissions. A short-haul return flight (e.g. London to Edinburgh) produces approximately 150 kg CO2e per passenger. A medium-haul flight (e.g. London to Berlin) produces around 350 kg CO2e, and a long-haul flight (e.g. London to New York) around 900 kg CO2e. These figures include radiative forcing, which accounts for the additional warming effect of emissions at altitude.

Remote working can reduce a company's Scope 1 and 2 emissions by reducing office energy consumption and eliminating employee commuting emissions. Studies suggest a typical remote worker reduces their work-related emissions by 50-70% compared to office working. However, home energy use increases and this should be factored in. Hybrid working patterns of 2-3 days per week offer a good balance between emission reduction and collaboration.