How to Compare UK Petrol and Diesel Prices Before a Drive

B& Business & Money Desk 2026-10-24 09:26 Updated: 09:54 4 min read

Fuel prices vary between forecourts, so the RAC’s UK averages can give you context but cannot tell you what a particular station charges. Before a long drive, compare the same type of fuel at live local stations, include any detour in the calculation and use your car’s real-world fuel economy to estimate the trip cost.

Use RAC Fuel Watch as a national benchmark

RAC Fuel Watch publishes average UK petrol and diesel prices. These figures help show the broad price level, but an average is not a quote for a station near your home or along your route. Local prices can differ, so check individual forecourts before deciding where to fill up.

Compare the benchmark with local listings for context, not as a guarantee of what you will pay. Prices can change, and the cost shown by a station or listing may not reflect the price when you arrive. Check live station prices again before setting off.

Read also: How to Compare UK Petrol Prices Before an Autumn Drive

Compare the same fuel at stations you can reach

Start with the fuel your vehicle uses. Compare petrol with petrol or diesel with diesel, and make sure any listing refers to the grade you normally buy. A cheaper figure for a different fuel or grade is not a like-for-like comparison.

Check stations near home or work as well as those on your planned route. For each option, consider the listed price, opening hours and how far you would have to leave your route. A lower price may not be worthwhile if reaching it adds a substantial detour.

Before you choose, check:

• The price for the correct fuel and grade.
• Whether the station is open when you expect to arrive.
• The extra distance needed to reach it and return to your route.
• Whether the price listing is current, then confirm it before departure.

Include the detour when comparing savings

A lower price per litre only saves money on the fuel you buy. If reaching a cheaper forecourt adds distance, your car will burn fuel on that detour too. The true comparison is the price saving minus the cost of driving the extra miles, along with any time the detour adds.

For example, multiply the price difference per litre by the litres you plan to buy to estimate the possible saving. Then estimate the detour’s fuel use from your own car’s real-world economy and multiply that by the price per litre. If the detour cost approaches or exceeds the saving, the cheaper station may not be the better choice.

Estimate your journey using your car’s real-world economy

Use the fuel economy you actually get, rather than relying only on a manufacturer’s figure. Your result can vary with traffic, speed, load, weather and driving conditions. Treat the calculation as an estimate, not a guaranteed cost. A guide to estimating journey fuel costs can help put those variables into a practical calculation.

For a car measured in miles per gallon (mpg), use:

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

The 4.546 factor converts UK gallons into litres. Use the price per litre for the fuel your car takes. If you track economy in miles per litre instead, divide the journey distance by that figure to estimate litres used, then multiply by the price per litre.

Worked example

Suppose a round trip is 240 miles, your car averages 40 mpg in your usual driving, and the fuel price you are checking is £1.50 per litre. The estimate is 240 ÷ 40 × 4.546 × £1.50, or about £40.91. This example shows the method; your own cost will depend on your actual economy and the price you pay.

Check live prices before setting off

Once you have compared stations and estimated the trip, check the prices again shortly before leaving. Confirm the forecourt’s current listing and opening hours, especially if you plan to refuel late or during a long journey. Keep a convenient station in mind in case your preferred stop is closed or its price has changed.

RAC Fuel Watch is useful for seeing average UK petrol and diesel prices. For a practical decision, pair that benchmark with current local station prices, a like-for-like fuel comparison and the cost of any detour.

Source: RAC

Context & actions About this article Report Share

Source check Price and cost method

RAC Fuel Watch publishes average UK petrol and diesel prices; local station prices and journey costs need checking for your own route and vehicle.

Checks

• Compare the same fuel and grade.
• Check current prices at individual stations.
• Include detour distance in the comparison.
• Estimate consumption from real-world vehicle economy.

Source

• RAC

RAC Fuel Watch Check local fuel prices

Source

RAC Fuel Watch

Scope

United Kingdom

Updated

2026-10-25 09:54

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