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Diesel costs 25.0p a litre more than petrol at the same pump
Diesel B7 averages 198.8p a litre across Britain and unleaded E10 averages 173.9p. The more useful comparison is at the 7,690 forecourts that sell both, where the difference between the two pumps on the same forecourt is 25.0p a litre, or £13.73 on a 55-litre tank. The duty on the two fuels is identical, so none of this gap is tax.
The gap is not tax
Fuel duty is the same rate on petrol and diesel, and VAT is the same percentage. Every penny of the difference happens before tax, in what the fuel costs to buy and refine and in what the retailer takes. Our breakdown of a litre shows where each part of the price goes.
It depends where you fill up
The gap is not the same everywhere, and the difference between kinds of forecourt is real.
| Kind of forecourt | Selling both | Diesel premium | Per tank |
|---|---|---|---|
| Supermarket forecourts | 2,234 | 24.8p | £13.65 |
| Motorway service areas | 159 | 20.7p | £11.39 |
| Everywhere else | 5,304 | 25.1p | £13.83 |
Where the two pumps are closest
At these forecourts diesel and unleaded are nearly the same price, which is as close as the market gets to treating them alike.
| Forecourt | Where | Unleaded | Diesel | Gap |
|---|---|---|---|---|
| Bells Centra | Newtownards, BT23 6PA | 193.9p | 168.9p | -25.0p |
| Riverside Garage | Gillingham, SP8 5RJ | 198.9p | 174.9p | -24.0p |
| Burnpark service station limited | Kilmarnock, KA1 4EL | 189.7p | 167.7p | -22.0p |
| Spar Markethill SS | Armagh, BT60 1PN | 199.9p | 179.9p | -20.0p |
| Rawcliffe bridge trading ltd | Goole, DN14 8NH | 169.9p | 157.9p | -12.0p |
| Papay community cooperative | Orkney, KW17 2BU | 180.0p | 175.0p | -5.0p |
| THORN HOUSE FILLING STATION | Penrith, CA10 1BL | 230.0p | 230.0p | 0.0p |
| Car Colston Fill Stn Ltd | Nottingham, NG13 8JA | 198.9p | 199.9p | 1.0p |
And where they are furthest apart
| Forecourt | Where | Unleaded | Diesel | Gap |
|---|---|---|---|---|
| Ravenspoint Trading Ltd | Isle Of Lewis, HS2 9QA | 142.9p | 201.9p | 59.0p |
| Hendrewenfillingstation | Tregaron, SY25 6QU | 166.9p | 212.9p | 46.0p |
| EG Long Eaton PFS | Nottingham, NG10 3JX | 150.9p | 196.9p | 46.0p |
| CSCM Holdings Ltd | Newry, BT34 5HP | 160.0p | 199.0p | 39.0p |
| PARC SERVICE STATION | Corwen, LL21 9EP | 167.0p | 205.0p | 38.0p |
| D D Evans & Sons Ltd, Service Garage | Lampeter, SA48 7JA | 169.9p | 206.9p | 37.0p |
| TERRY &EVERTON | Aberteifi, SA43 2SL | 168.9p | 205.9p | 37.0p |
| Embleton Garage | Alnwick, NE66 3XR | 170.9p | 206.9p | 36.0p |
Diesel is cheaper than petrol at 6 forecourts
Most drivers take it as given that diesel costs more. At 6 of the 7,690 forecourts selling both, it does not. That is 0.1% of them, and it is a reminder that the national average describes the market rather than your street.
The dearest places for diesel
| Town | Forecourts | Typical diesel | Cheapest there |
|---|---|---|---|
| Isle Of Arran | 4 | 216.1p | 213.0p |
| Brighouse | 4 | 209.4p | 190.9p |
| Shetland | 13 | 206.9p | 201.9p |
| Pwllheli | 4 | 205.9p | 205.9p |
| Dagenham | 6 | 204.9p | 196.9p |
| Isle Of Islay | 4 | 203.9p | 196.9p |
| Honiton | 5 | 203.9p | 193.9p |
| Ashington | 4 | 203.9p | 199.9p |
What this page does not tell you is which fuel is cheaper to run, because that depends on the car and we hold prices rather than consumption. A diesel doing more miles to the gallon can be cheaper per mile while costing more per litre. We are not going to guess at your mileage.
How this is measured
Unleaded E10 and diesel B7, the two grades most drivers buy. The headline gap uses only the 7,690 forecourts reporting both, so it compares two pumps on one forecourt rather than two different sets of sites. Forecourts whose prices have not moved in 14 days are excluded, and so are prices more than 25% from the national median for their grade. Data as at 2026-09-25.
Source: the government Fuel Finder scheme, run by the Department for Energy Security and Net Zero, which retailers are legally required to submit to. Figures recalculated on every build.