How to Compare Petrol and Diesel Prices in the UK

A cheaper price per litre does not always mean a cheaper journey: compare the total cost of the fuel you need and allow for the distance to the forecourt. The Competition and Markets Authority (CMA) publishes UK road fuel monitoring information, but a national figure cannot tell you what every station near you charges today.

Compare nearby forecourts by total cost

Start with the fuel type your vehicle requires, then compare the displayed price per litre at stations you could reasonably visit. Petrol and diesel prices are separate, and the cheapest option can vary between nearby forecourts.

Use this simple calculation for each station:

Litres you plan to buy × price per litre = fuel cost

For example, if you buy 40 litres at £1.50 per litre, the fuel costs £60. If another station charges £1.47 per litre, the same 40 litres costs £58.80, a difference of £1.20 before accounting for the journey to that station.

The example uses hypothetical prices; it is not a current UK price quote. Check prices displayed by stations or a fuel finder before you set out, since prices can change and local prices differ.

Include the detour in your comparison

A station farther away may erase the saving through the extra fuel used to reach it. Estimate the added distance for the round trip, then consider your vehicle’s fuel consumption and the cost of that extra fuel. If the trip is already on your route, the added distance may be small; a special journey needs a more careful comparison.

A practical check is to compare the expected saving on your planned fill-up with the estimated cost of the detour. If the saving is only a small amount, a longer drive may not be worthwhile. Your result will depend on your vehicle, traffic, route and how many litres you buy.

Also compare like with like: use the same number of litres in each calculation, and make sure you are checking the fuel grade your vehicle needs. A price difference per litre matters more on a larger fill-up, but it still needs to be weighed against travel distance.

Calculate the cost of the fill-up you need

Multiply the litres you expect to buy by the price shown at the pump. If you usually fill a known amount, use that figure; if you stop when the tank reaches a certain level, estimate the litres needed rather than comparing prices alone.

For instance, at a hypothetical price of £1.52 per litre, a 30-litre purchase would cost £45.60. A 50-litre purchase at the same price would cost £76. These examples show how the quantity bought changes the total; they do not indicate today’s forecourt prices.

If you are comparing two stations, calculate both totals using your expected litres. Subtract the lower total from the higher one to find the price saving, then assess whether the extra distance is likely to cost less than that saving. Treat the result as an estimate because driving conditions and actual fuel use vary.

Check current local prices before setting off

Use a fuel finder that shows prices for nearby forecourts, where available, and check when its information was last updated. Confirm the price at the station if the listing may be old. The CMA’s GOV.UK collection brings together its road fuel price monitoring publications and related data; it provides context on the market, but does not guarantee a live price for each local pump.

A national average can help describe the wider market at a particular date, but it is not a promise of the price in your town or at a specific forecourt. When using an official price figure, check its publication date, fuel type and geographic coverage. For a decision about where to fill up now, nearby station prices are more useful than an undated average.

Before you leave, compare the price, the quantity you expect to buy and the added route distance. Recheck the displayed price when you arrive, since a listing or earlier figure may no longer match the pump.

Source: Competition and Markets Authority via GOV.UK