Why is diesel more expensive than petrol?

Diesel and petrol prices across the UK

These UK averages come from 6,893 forecourts with a petrol price and 6,341 with a diesel price in our price data. We update it every 15 minutes. See how we work them out.

Most of the prices behind both averages are more than 3 days old.

Updated 6:47am on 2 November.

The short answer

On our latest figures, diesel (B7) averages 198.4p a litre across UK forecourts, 26.7p more than petrol (E10) at 171.7p. On a 55-litre fill that is £14.69 more. Fuel duty is 52.95p a litre on both^[1]. Diesel costs more before tax, and VAT at 20% is charged on that difference too^[1].

Average petrol (E10) and diesel (B7) prices across UK forecourts each day since 7 February 2026.

• On 1 November, diesel cost 26.7p a litre more than petrol.
• The gap was up 1.1p over the week, and up 1.4p over 30 days.
• On 7 February 2026, when our daily figures start, it was 9.1p.
• The widest it has been is 33.5p, on 13 April.
• Since then the narrowest has been 13.5p, on 12 July.

Figures to 1 November 2026.

Daily UK averages from our price data.

For each day's UK averages of all four fuels, see our UK fuel price index.

Why diesel costs more

The same duty, more VAT

Fuel duty is 52.95p a litre on petrol and diesel alike, so it adds nothing to the gap^[1]. VAT at 20% is charged on the fuel and the duty together^[1]. Of the latest 26.7p gap, 22.2p is the difference before tax and 4.5p is VAT on it. How fuel duty works.

The UK has spare petrol and imports diesel

DESNZ says the UK "is more than self-sufficient for petrol, so petrol is typically around half the product export total"^[2].

The UK relies on imports for much of its diesel. In 2025, "just under 40 per cent of product imports were diesel"^[2].

The United States supplied 31% of that diesel, the Netherlands 26% and Belgium 11%^[2].

On DESNZ's 2025 balance tables, UK refineries made about 115% of the petrol the UK used, and about 52% of its diesel^[2].

UK refinery output was 48 million tonnes in 2025, down 4.8% on 2024. That year the Grangemouth refinery became an import terminal and the Prax Lindsey refinery closed^[2].

Diesel vehicles, meaning cars, goods vehicles and buses, made up over 45% of UK transport fuel demand in 2025^[2].

More energy in a litre

On DESNZ figures, a litre of diesel holds about 35.8 MJ of energy and a litre of petrol about 33.2 MJ^[3]. That is about 8% more energy in a litre of diesel.

Why tax and refining cost don't explain it

Tax doesn't explain the gap, since duty is the same on both fuels^[1].

In our figures the gap went from 9.1p on 7 February 2026 to 33.5p on 13 April, then back to 13.5p on 12 July. A fixed cost of refining couldn't move the gap that far in a few months. The CMA's reports, in the next section, trace the rise to the refining spread and the slower fall to delayed retailer responses^[4][5].

Why the gap jumped in 2026

The CMA said in May 2026 that from the end of February to the week of 20 April, diesel rose 49.8p a litre. Petrol rose 25.9p^[4].

In its figures, crude oil added about the same to each fuel: 10.0p to diesel and 10.3p to petrol. The refining spread rose 15.1p on diesel and 7.9p on petrol^[4].

In the CMA's terms, the refining spread is the wholesale price set by refineries and importers, less the cost of the crude oil in it^[4].

By the week of 20 April, the CMA said, the diesel refining spread was "almost two times the petrol refining spread". It said this reflected "differences in international trading conditions"^[4].

In May 2026 the CMA gave its reason. Diesel, it said, "is part of the middle-distillates product group, where global refinery capacity is currently tighter relative to global demand"^[4].

The CMA's retail spread is what is left of the pump price after duty, VAT, wholesale and biofuel costs. On diesel it went from 11.4p at the end of February to minus 10.1p in mid-March, then 26.8p in the week of 20 April. On petrol it went from 12.0p to 0.8p, then 13.9p^[4].

The CMA said the fall and rebound in that spread, particularly for diesel, was probably down to the lag before wholesale costs reach pump prices^[4].

Over the same weeks, VAT added 8.3p to the price of diesel and 4.3p to petrol, on the CMA's figures^[4].

Petrol and diesel refining spreads also split in mid-2022, after Russia invaded Ukraine, the CMA noted. That split narrowed over the following months^[4].

In August 2026 the CMA said diesel pump prices had come down more slowly than wholesale costs. Lagged diesel spreads tended to stay above their pre-conflict level until the end of June, while petrol spreads did not^[5].

It said this "suggests that retailer responses to reductions in wholesale diesel costs may have been more delayed"^[5].

The CMA also said it had not found evidence that retailers "actively changed their pricing strategies to take advantage of the crisis"^[5].

From March to June, average retailer margins stayed "at or above the historically high level observed in 2025", the CMA said in August 2026^[5].

Was diesel ever cheaper than petrol?

Yes, for short spells. The government's weekly price survey began in June 2003. Up to the week of 12 October 2026, it shows diesel cheaper than petrol in 13 weeks^[6].

Those weeks ran from 3 August to 21 September 2015, and from 1 to 29 February 2016. From 7 March 2016 to 12 October 2026, diesel cost more every week^[6].

From 2003 to 2021, the median week had diesel 4.22p a litre dearer than petrol. The widest weekly gap in the survey was 33.97p, in the week of 13 April 2026^[6].

We worked these figures out from the DESNZ data, to the week of 12 October 2026.

Before the survey, DfT's April price tables show diesel a little cheaper than petrol in April each year from 1990 to 1993. Diesel duty was slightly lower than petrol duty in those years^[7].

The gap by brand and region

Among the brands below, the gap runs from 23.9p at Go to 28.4p at Emo.

Supermarket diesel averages 195.9p, 25.9p more than supermarket petrol at 170.0p. At the major brands diesel is 27.0p more than petrol.

Each brand's average petrol and diesel price at its own forecourts, not counting motorway services, smallest gap first.

Brand averages from our price data, from each brand's forecourts away from motorway services.

Figures marked † are mostly from prices over 3 days old.

By region, the gap runs from 26.0p in the North West to 28.0p in the North East.

Regional averages from our price data, across every forecourt in each region.

Figures marked † are mostly from prices over 3 days old.

Regional averages updated 6:47am on 2 November.

Petrol or diesel: which costs less to run?

At the latest averages, diesel costs 15.6% more a litre than petrol. So a diesel car needs more than 15.6% better mpg than a petrol car to cost less per mile.

Take the fuel economy we use across the site: 44.6 mpg for a petrol car and 48.4 mpg for a diesel. That is 8.5% better for diesel. At the latest prices, the diesel car costs more to run: about £90 more over 8,000 miles a year, or about £135 over 12,000.

Prices are the UK averages at the top of the page, from our price data.

Diesel's mpg lead shrinks as speed rises, and at motorway speeds petrol is slightly ahead. How we chose these mpg figures.

This covers fuel only. Purchase price, servicing, insurance and clean air zone charges also differ between cars, and this page doesn't cover them.

Work out what a journey costs in petrol or diesel.

Search for a station near you. Each station page has a fill-up calculator.

Common questions about diesel and petrol prices

Sources and method

1. GOV.UK: Tax on shopping and services, Fuel Duty, checked 13 October 2026.
2. GOV.UK (DESNZ): DUKES 2026 Chapter 3: Oil and oil products, checked 15 October 2026.
3. GOV.UK (DESNZ): DUKES calorific values and density of fuels (Annex A), checked 15 October 2026.
4. GOV.UK (CMA): Enhanced road fuel monitoring report: May 2026, checked 15 October 2026.
5. GOV.UK (CMA): Enhanced road fuel monitoring report: August 2026, checked 15 October 2026.
6. GOV.UK (DESNZ): Weekly road fuel prices, checked 15 October 2026.
7. GOV.UK (DfT): Transport energy and environment data tables, ENV0105: petrol and diesel prices and duties per litre in April, checked 15 October 2026.

Our figures: each UK average is over every forecourt's latest price reported in the last 30 days, leaving out prices far from what the rest of the UK charges. The brand figures leave out motorway services too. The VAT split takes the same duty on both fuels and VAT at 20%. How we work out the figures