How to Compare Petrol and Diesel Prices Before a UK Journey

Planning a UK drive? Check current petrol or diesel prices near your route, then estimate how much fuel the journey will use. Prices differ by station, location and date, and a cheaper pump can cost more overall if reaching it adds a long detour.

Check current prices near your route

Start with the UK Government’s road fuel prices guidance, which directs drivers to information about comparing prices. The Competition and Markets Authority (CMA) also provides fuel-finder information to help people look up local prices. Check the guidance for the latest links and details on how to use available tools.

You can also consult RAC Fuel Watch for information and analysis about UK petrol and diesel prices. It can help you understand wider price movements, but your trip budget depends on the price you can actually find at a station along your route.

Before setting off, compare stations close to your starting point, destination and planned route. Check that the listing is recent, that it is for the right fuel type, and that the station is open when you expect to arrive. Prices can change, so confirm the figure close to your journey rather than treating an old result as a guarantee.

Estimate fuel cost with your car’s real-world mpg

For a UK car measured in miles per gallon, convert the pump price from pence per litre to pounds per litre, then convert imperial gallons to litres. One imperial gallon is about 4.546 litres. Use this calculation:

Journey distance in miles ÷ real-world mpg × 4.546 × price per litre in pounds = estimated fuel cost

For example, suppose a one-way journey is 180 miles, the car averages 40 miles per imperial gallon in real-world driving, and fuel is £1.50 per litre. The estimate is 180 ÷ 40 × 4.546 × £1.50, or about £30.69. This is an illustration, not a current UK price.

If the pump price is shown in pence, divide it by 100 before using the formula. At 150p per litre, for example, the price is £1.50 per litre.

Use the vehicle’s likely real-world efficiency rather than relying only on its official figure. Stop-start traffic, speed, weather, passengers, luggage and driving style can all affect consumption. If you are unsure, use a recent figure from your own driving and allow a margin for changing conditions.

For a return trip, double the distance if you expect to retrace the same route. If your outward and return routes differ, estimate each leg separately. The same method works for petrol and diesel; select the price for the fuel your vehicle takes.

Decide whether a cheaper station is worth the detour

Compare the saving on the fuel you plan to buy with the cost of driving out of your way. A lower price per litre does not automatically make a station cheaper overall: the detour uses fuel and adds time, and the listed price may have changed by the time you arrive.

A practical check is to estimate the detour’s fuel cost using the same formula. Compare that amount with the saving on the litres you expect to buy. For instance, if a detour adds 10 miles, your car averages 40 mpg, and fuel is £1.50 per litre, the extra driving uses about 1.14 litres, costing roughly £1.70. The station’s lower price would need to save more than that on your purchase to offset the extra fuel, before considering time or other costs.

The amount you buy matters. A small price difference can add up over a large fill, but may barely offset a lengthy detour if you only need a few litres. If you have enough fuel to choose among several stations on your route, comparing prices without leaving the route may be the simpler option.

Make a quick pre-trip comparison

Before you leave:

• Look up recent prices for the correct fuel near your route using fuel-finder information and other current listings.
• Check the station’s location, opening hours and how far it is from your planned route.
• Estimate journey fuel from distance, your car’s real-world mpg and the price per litre.
• Add the cost of any detour, then compare it with the likely saving on your planned purchase.
• Recheck the price if your journey is later or conditions have changed.

Prices vary by place, station and date, so there is no single local result that will apply to every driver. For the most useful estimate, check a current listing for the fuel you need and use your own vehicle’s consumption and actual route.

Source: UK Government