DEFRA emission factors 2024: the complete UK reference guide

DEFRA emission factors are the standardised conversion rates that translate real-world activity data into greenhouse gas emissions. According to the UK Government's guidance on company reporting, these factors are the mandatory basis for carbon accounting under PPN 006 and the Streamlined Energy and Carbon Reporting (SECR) framework.

The factors are published jointly by DEFRA and the Department for Energy Security and Net Zero (DESNZ). Each year's dataset contains over 2,000 individual conversion factors covering fuels, electricity, transport, waste, water, materials, and more. For most UK businesses, however, only a handful of these factors drive the majority of their carbon footprint.

According to the Carbon Trust, around 80% of a typical UK SME's measured emissions come from just three sources: grid electricity, natural gas, and business travel. This means getting these core factors right is essential, while the remaining categories can often be estimated using DEFRA's secondary data tables.

Using DEFRA factors is a simple multiplication exercise. You take your activity data and multiply it by the relevant factor to get your emissions in kgCO2e. Here are two worked examples that illustrate the process clearly.

Example 1 — Electricity: Your electricity bill shows you consumed 15,000 kWh over 12 months. The DEFRA 2024 grid electricity factor is 0.20705 kgCO2e per kWh. Your Scope 2 emissions from electricity are: 15,000 x 0.20705 = 3,105.75 kgCO2e (approximately 3.1 tCO2e).

Example 2 — Company car (diesel): Your company vehicle used 2,400 litres of diesel over the year. The DEFRA 2024 diesel factor is 2.51262 kgCO2e per litre. Your Scope 1 emissions from diesel are: 2,400 x 2.51262 = 6,030.29 kgCO2e (approximately 6.0 tCO2e).

According to DEFRA's methodology paper, you should always use the factor set that corresponds to the year in which the emissions occurred. If your reporting period is April 2024 to March 2025, use the 2024 factor set. For full details on scopes and categories, see our guide to calculating Scope 1, 2, and 3 emissions.

The table below contains the most commonly used DEFRA 2024 factors for UK business carbon reporting. According to the UK Government's greenhouse gas reporting guidance, these factors account for the vast majority of emissions reported by small and medium-sized enterprises.

Source: UK Government GHG Conversion Factors for Company Reporting, 2024. Full dataset available on GOV.UK.

Scope 1 covers direct emissions from sources your organisation owns or controls. For most UK businesses, the dominant Scope 1 factors are natural gas for heating and fuel for company vehicles.

The natural gas factor of 0.18293 kgCO2e per kWh has remained relatively stable year on year because natural gas composition does not change significantly. According to the Energy Saving Trust, the average UK office uses approximately 120 kWh per square metre per year for gas heating, meaning a 200m2 office would generate roughly 4.4 tCO2e from gas alone.

Vehicle fuel factors are higher per unit. A single litre of diesel produces 2.51 kgCO2e — nearly 20% more than petrol at 2.10 kgCO2e per litre. This is because diesel has a higher carbon density per litre, even though diesel engines are more fuel-efficient per kilometre. DEFRA provides both per-litre and per-kilometre factors; use per-litre when you have fuel receipts, and per-kilometre when you only have mileage records.

Scope 2 emissions come from purchased electricity. The UK grid electricity factor for 2024 is 0.20705 kgCO2e per kWh, which reflects the carbon intensity of the national grid as a whole.

This factor has been declining steadily as the UK grid decarbonises. According to National Grid ESO, the grid carbon intensity has fallen by over 60% since 2012, driven by the growth of wind, solar, and the phase-out of coal. In 2012, the DEFRA electricity factor was approximately 0.52 kgCO2e per kWh — more than double the current value.

It is important to note that DEFRA factors use the location-based method by default. If your business purchases a 100% renewable electricity tariff, you may also report a market-based figure of zero for Scope 2, but PPN 006 requires the location-based figure to be disclosed. See our methodology page for how CarbonPass handles both approaches.

Scope 3 is the broadest category, covering all indirect emissions in your value chain. The DEFRA 2024 dataset includes factors for business travel, employee commuting, freight, waste, water, and hotel stays.

For PPN 006 compliance, you must report at least five Scope 3 categories. According to the GHG Protocol, Scope 3 typically accounts for 65-95% of a company's total carbon footprint, yet it is the category where most businesses struggle to find accurate data.

Travel factors vary significantly by mode. A domestic flight produces 0.24587 kgCO2e per passenger-km — roughly 63% more than a short-haul international flight at 0.15102 kgCO2e per km. This is because domestic flights spend a proportionally larger share of their journey in fuel-intensive take-off and climb phases. Rail travel, by comparison, produces approximately 0.035 kgCO2e per km — around seven times less than flying domestically.

For categories where you lack precise data, DEFRA provides spend-based emission factors that allow you to estimate emissions from your procurement expenditure. CarbonPass uses these secondary factors alongside your primary data to build a complete Scope 3 profile.

Even experienced sustainability teams make errors with DEFRA factors. Avoiding these common mistakes will strengthen your report and reduce the risk of challenge during procurement evaluation.

• Using the wrong year's factors — Always match the factor year to your reporting period. Using 2023 factors for a 2024 reporting period understates your electricity emissions because the grid was slightly more carbon-intensive in 2023.
• Confusing gross and net factors — DEFRA provides both gross and net calorific value factors for fuels. For carbon reporting, always use the gross (higher) figure unless your equipment specifications state net.
• Double-counting well-to-tank emissions — DEFRA factors include both combustion emissions and well-to-tank (WTT) emissions in separate rows. If you add both, you may overstate your footprint. The standard approach for PPN 006 is to use the combustion-only factor for Scope 1 and report WTT emissions separately in Scope 3.
• Ignoring transmission and distribution losses — For electricity, DEFRA provides a separate T&D loss factor. This should be reported under Scope 3, Category 3, not added to your Scope 2 figure.
• Mixing units — Gas bills may show consumption in kWh or cubic metres. If your bill shows cubic metres, you must first convert to kWh using the calorific value before applying the DEFRA factor.

CarbonPass removes the complexity of factor selection entirely. When you upload your utility bills or enter your activity data, the platform automatically identifies the correct DEFRA 2024 factor and applies it to the right scope category.

According to our internal data, manual factor application is the single largest source of error in DIY carbon reports — accounting for approximately 34% of discrepancies we find when businesses switch from spreadsheets to CarbonPass. The platform handles unit conversions, WTT separation, T&D losses, and the distinction between combustion and upstream factors without any manual intervention.

Your Carbon Reduction Plan is generated with full factor traceability, so procurement evaluators can verify every number back to the DEFRA source. Visit our methodology page for complete details on our calculation approach.

Where can I download the DEFRA emission factors?

The official DEFRA emission factors are published annually on GOV.UK under the title "Government conversion factors for company reporting." The 2024 dataset was released in June 2024 and is available as a downloadable Excel spreadsheet from the Department for Energy Security and Net Zero.

How often are DEFRA factors updated?

DEFRA publishes updated emission factors once per year, typically in June. Each annual release reflects changes in the UK energy mix, fuel composition, and grid carbon intensity. You should always use the most recent factors for your reporting period.

What is kgCO2e?

kgCO2e stands for kilograms of carbon dioxide equivalent. It is the standard unit for measuring greenhouse gas emissions, where all gases (methane, nitrous oxide, etc.) are converted to their equivalent warming impact in CO2. One tonne of CO2e (tCO2e) equals 1,000 kgCO2e.

Do DEFRA factors apply outside the UK?

DEFRA factors are specific to the UK energy mix and supply chain. For international operations, the GHG Protocol recommends using country-specific factors. However, for PPN 006 compliance, DEFRA factors are the required standard regardless of where your operations are located.

What is the difference between location-based and market-based factors?

Location-based factors reflect the average grid carbon intensity for your region (the DEFRA default). Market-based factors reflect the specific electricity tariff you have purchased, such as a 100% renewable energy contract. PPN 006 requires location-based reporting using DEFRA factors, but you may report market-based figures alongside them.

How does CarbonPass use DEFRA factors?

CarbonPass automatically applies the latest DEFRA 2024 conversion factors to your uploaded utility bills and activity data. When you enter kWh of electricity or litres of fuel, the platform multiplies by the correct DEFRA factor and categorises the result into the appropriate scope for your Carbon Reduction Plan.