Why Fuel Prices Change

Fuel prices change for four reasons, and only one of them is the oil price. The others are the exchange rate, the retailer's own margin decision, and local competition. Across the 7,986 forecourts we track, the same grade of unleaded ranges from 132.9p to 239.9p on the same day - a spread no movement in crude can explain.

The four things that move a pump price

• The wholesale product price, driven by crude oil and refining margins. Moves daily, reaches the pump slowly.
• The pound against the dollar, because oil is traded in dollars. A weaker pound raises fuel costs even when oil is flat.
• Duty and VAT, which change only at fiscal events but make up nearly half the price.
• The retailer's margin, set site by site. This is the one that varies between two forecourts on the same road.

Why crude oil explains less than you would think

Duty is a flat 52.95p per litre regardless of what oil does. VAT is 20% on top of everything. Together they are roughly half the pump price and are completely insensitive to the oil market on any given day.

On top of that, the fuel in a forecourt's tanks was bought weeks ago. A retailer sells through existing stock before the new wholesale price reaches the pump, which is why a sharp fall in crude takes weeks to appear and often arrives smaller than expected.

The part that changes street by street

Tax is identical everywhere in the UK. Wholesale costs vary only slightly. So when you see a large difference between two nearby stations, you are almost entirely looking at different margin decisions.

The 11.2p gap between the cheapest and dearest major brand is a commercial choice, not a cost difference. On a 55-litre fill that is £6.16.

Prices rise faster than they fall

The pattern is well documented: when wholesale costs rise, pump prices follow within days; when they fall, the pump takes considerably longer. The Competition and Markets Authority examined this in its road fuel market study and concluded that competition in the sector had weakened, with retailer margins widening. The open data scheme behind the prices on this site was one of the direct outcomes.

Seasonal and regional effects are real but small

Demand rises over summer holidays and around Christmas, and winter blends cost slightly more to produce. Rural areas with a single forecourt and a long delivery run are consistently dearer. Both effects are measurable, but both are smaller than the difference between a supermarket and a motorway services on the same day.

You can see how your own area compares on our UK fuel price index, or check the current standing of every brand.

Frequently asked questions

Why did prices go up the day after oil went up, but not down when it fell?

Retailers reprice quickly when their replacement cost rises, because the next delivery will cost more. When wholesale falls, there is less commercial pressure to pass it on until a competitor does. The CMA identified this asymmetry in its market study.

Does the exchange rate really matter?

Yes. Oil is priced in dollars, so a weaker pound raises the cost of every litre imported even if the barrel price has not moved. It is a quiet driver that rarely makes the headlines.

How often do prices actually change?

Individual forecourts typically reprice every few days rather than daily, though supermarkets often move together within 24 hours of each other. We refresh our data throughout the day.

Will prices come down?

We do not forecast. What the data reliably shows is that on any given day there is a 10p or larger gap between the cheapest and dearest stations within most towns, and that gap is available to you now regardless of where the market goes next.

Figures updated 29 August 2026. Based on live prices from 7,986 UK forecourts supplied through the CMA's open fuel price scheme and refreshed throughout the day. Duty rates from HMRC.