Diesel (forecourt) emission factor 2026 (UK, kg CO2e per litre)

The 2026 UK government emission factor for diesel (forecourt) is 2.5835 kg CO2e per litre, reported as Scope 1. That is 0.5% higher than the 2025 factor of 2.5708. Including well-to-tank, the full figure is 3.1946 kg CO2e per litre.

Updated 3 October 2026 by the Carbon Recycling team. Figures use the official UK government conversion factors and are checked against the current gov.uk guidance.

Diesel (forecourt) emission factor by year

Year	Scope 1 (kg CO2e per litre)	Well-to-tank	Full figure	Change
2026	2.5835	0.61101	3.1946	+0.5%
2025	2.5708	0.61101	3.1818	+2.3%
2024	2.5128	0.61101	3.1238	+0.0%
2023	2.5121	0.61101	3.1231	-1.8%
2022	2.5578	0.60986	3.1677	+1.8%
2021	2.5123	0.60986	3.1222	-1.3%
2020	2.5460	0.61015	3.1562	-1.9%
2019	2.5941	0.61709	3.2112	–

Total kg CO2e for the seven greenhouse gases, from the official DESNZ files for each year. 2026 factor ID: 1_101_1011_8_1. Where a factor jumps sharply between two years, it is usually because DESNZ changed its method or data source, not because the activity itself changed.

Worked example

Take a fleet of five vans buying 20,000 litres of diesel a year. 20,000 litres × 2.5835 kg CO2e = 51.67 tonnes CO2e, reported as Scope 1. Adding well-to-tank brings the full figure to 63.89 tonnes CO2e; the extra 12.22 tonnes are Scope 3 category 3.

How to report it

This is the factor for diesel bought at UK forecourts, which contains a share of biodiesel. The biofuel part's CO2 is reported outside of the scopes, so the Scope 1 factor is a little lower than for pure mineral diesel.

Fuel bought for vehicles your business owns or leases is Scope 1. Fuel for employees' own cars that you reimburse by the mile is Scope 3 business travel instead; use the car factors for those miles.

Litres are the most accurate way to report vehicle emissions. Use them whenever you have fuel cards, and only fall back to mileage when you don't.

Where the data comes from

You'll usually find it in fuel card statements or fuel receipts, in litres. Keep the source documents: anyone checking your Carbon Reduction Plan or SECR report may ask how each figure was worked out.

To convert your own figures straight away, use our free kWh to CO2e calculator, which shows 2026 and 2025 side by side.

Read more about how the factors change each year in our guide to the 2026 conversion factors, or see how we apply them in our methodology.

Related emission factors

Petrol (forecourt): 2.0750 kg CO2e per litre
Average diesel van (up to 3.5 tonnes): 0.41386 kg CO2e per mile
Gas oil (red diesel): 2.7554 kg CO2e per litre
All UK emission factors

Frequently asked questions

Which year's factor should I use?

The set for the year your reporting period falls in. If your financial year spans two calendar years, use the set for the calendar year most of it falls in, and keep the same rule every year. Don't restate past years with new factors unless you are correcting an error.

Is this the DEFRA factor?

Yes. The UK government conversion factors used to be published by DEFRA, then BEIS, and since 2023 by the Department for Energy Security and Net Zero (DESNZ). Many people still call them the DEFRA factors.

Do I need to include well-to-tank emissions?

They are Scope 3 category 3 (fuel- and energy-related activities). SECR doesn't require them, and PPN 006 doesn't list category 3 among its required Scope 3 categories, but including them gives a more complete footprint and some customers ask for them.

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