What you are actually paying for
A litre of fuel is mostly tax. Fuel duty is a flat 52.95p on every litre of petrol and diesel alike, charged before value added tax, and then VAT at 20% is applied to the whole lot, duty included. Only what is left over covers the fuel itself, getting it to the forecourt, and the retailer’s margin. Here is how today’s typical UK price divides up.
| Per litre | Fuel duty | VAT | Fuel, delivery and retailer | Typical price |
|---|---|---|---|---|
| Unleaded (E10) | 52.95p | 26.98p | 81.97p | 161.9p |
| Diesel (B7) | 52.95p | 30.48p | 99.47p | 182.9p |
That puts tax at about 49% of the pump price of unleaded and 46% of diesel. Two consequences follow, and they explain a great deal about how fuel prices behave. Because duty is a fixed amount rather than a percentage, it does not rise when wholesale prices rise, so a doubling of the oil price does not double what you pay. And because VAT is charged on top of duty, the government collects a little more VAT whenever the price at the pump goes up.
Fuel duty is scheduled to change. The temporary 5p cut introduced in March 2022 has been extended repeatedly, and under the current schedule the rate rises to 55.95p a litre on 1 January 2027, with a further step after that. Each penny of duty adds 1.2p to the pump price once VAT is applied.
Why two forecourts a mile apart charge different prices
Every retailer in the country pays broadly the same duty and buys from the same wholesale market, so the differences you can see on this site come almost entirely from the last part of the chain: what each site decides to charge. The main things that move it are:
- How much competition is within sight. This is the single biggest factor. A forecourt with three rivals within two miles prices very differently from the only one in fifteen. It explains most of the rural premium, which is about isolation rather than delivery costs.
- Whether it is a supermarket. Supermarkets have historically used fuel to bring people to the store rather than to make money in its own right, so they price near cost.
- Whether it is a captive location. Motorway services are the clearest case: nobody chooses one for the price, so they charge substantially more than the same brand does a mile off the junction. Airports and some trunk roads behave the same way.
- Volume. A busy site earns the same profit from a thinner margin, and can afford to undercut a quiet one.
- When the last delivery arrived. A forecourt is still selling the fuel it bought a few days ago, so when wholesale prices fall sharply, the sites that turn stock over fastest cut first.
The scale of it is easy to underestimate. Across the 407 towns on this site with at least five forecourts, the typical gap between the cheapest and the dearest unleaded in the same town is 9.0p a litre. For a car covering 10,000 miles a year at 45 miles per gallon, which uses roughly 1,010 litres, always using the cheaper end of your own town is worth about £91 a year. That is before comparing towns, and it requires no detour at all.
By brand, the national spread today runs from a median of 151.9p at Go up to 186.9p at Welcome Break, a difference of 35.0p a litre. The two ends of that range are not really a story about brands. The cheapest end is normally supermarkets and independents in towns with plenty of competition, and the dearest end is normally the motorway service operators, whose customers have nowhere else to go. The full table is on the prices by brand page and it moves week to week.
Rockets and feathers
Pump prices are widely observed to rise quickly when wholesale costs rise and to fall slowly when they fall, a pattern economists have named rockets and feathers. The Competition and Markets Authority found the effect in the United Kingdom road fuel market during its 2022 and 2023 investigation, along with a broader finding that retailer margins on fuel had widened materially since 2019, costing motorists a substantial sum. The statutory price-reporting scheme that supplies the data on this site exists as a direct result of that work.
The practical consequence for a driver is that the weeks after a fall in oil prices are exactly when forecourts differ from each other most, because some pass the fall on within days and others take a month. Those are the weeks when checking before filling up is worth the most.
What actually saves money, in order of size
- Fill up at the cheaper end of the places you already pass. Worth roughly £91 a year for an average car, with no extra driving.
- Avoid filling at motorway services. The premium there is typically well into double figures in pence per litre. A forecourt a mile from the junction is usually enough to avoid it. Our motorway services page shows the current gap.
- Use the loyalty price if there is one. Several supermarket chains now run a members-only price at the pump. The published price this site receives is the standard one, so a loyalty card can beat everything shown here at that site.
- Do not buy super unleaded unless the car needs it. E5 costs a good deal more per litre and makes no difference to an engine designed for E10.
- Keep the tyres at the right pressure and the boot empty. Underinflated tyres cost a small but permanent percentage of fuel economy, and it is free to fix.
- Do not drive out of your way. A six-mile round trip burns about 0.6 litres, so on a 50-litre fill the detour only breaks even if the destination is more than about 2.0p a litre cheaper.
Where these prices come from
Every figure on this site comes from Fuel Finder, the government scheme under which fuel retailers in the United Kingdom must publish their pump prices and report any change within 30 minutes. It covers 8,075 forecourts. We show the prices exactly as retailers report them, with no filtering by brand and no ranking that favours one retailer over another, and every station page carries a link for reporting a figure that looks wrong. The underlying data, and a full description of how it is processed, are on the data and how it works pages, and the whole dataset can be downloaded.
Questions people ask
How often do these prices change?
Retailers are required to report a price change within 30 minutes of making it, and this site rebuilds through the day from the resulting feed. The time of the newest change we hold is shown above. A forecourt that has not moved its price for a while will simply show the same figure, which is normal rather than a sign of stale data.
Why is the price on the pump sometimes different from the price here?
Three reasons account for almost all of it. The retailer changed the price in the last few minutes and the change has not reached us yet. The forecourt reported the figure incorrectly, which happens occasionally and is why every station page carries a way to report an error. Or the price you saw was a members-only or loyalty price rather than the standard one that has to be published. Prices here are shown exactly as the retailer reported them, without filtering.
Why is diesel more expensive than petrol when it used to be cheaper?
Both carry identical fuel duty, so the difference is entirely in the wholesale product and the retailer margin. Diesel is refined and traded as a global product with strong demand from heavy goods vehicles, agriculture and heating in some countries, and European refining capacity for it has been tight since 2022. Retailers have also been shown to hold wider margins on diesel than on petrol. The gap between the two moves with wholesale markets rather than with anything the government sets.
Do supermarkets really sell fuel more cheaply?
On average yes, and the gap is measurable in the data on this site. Supermarkets treat fuel as a way of getting people onto the site rather than as a profit centre in itself, so they price close to cost and accept a thin margin. The competition authority has found that even supermarket margins widened after 2019, so the saving is smaller than it once was, but it is still real. What matters more than the brand, though, is how many competing forecourts sit within a couple of miles.
Is it worth driving further for cheaper fuel?
Rarely, and the arithmetic is easy to do. A car returning 45 miles per gallon burns about a tenth of a litre per mile, so a six-mile round trip uses roughly 0.6 litres of fuel. On a 50-litre fill, a detour like that only pays for itself if the cheaper forecourt is more than about 2.0p a litre cheaper, before counting the time. Filling up at the cheapest place you already pass is worth far more than seeking one out.
What is E10, E5, B7 and HVO?
E10 is standard unleaded petrol with up to 10% bioethanol, and it is what almost every petrol car sold since 2011 runs on. E5 is super unleaded, with up to 5% bioethanol and a higher octane rating; a small number of older or high-performance engines need it. B7 is standard diesel with up to 7% biodiesel and B10 has up to 10%. HVO is hydrotreated vegetable oil, a renewable diesel substitute sold at a small and growing number of sites, listed on our HVO page.