UK fuel prices: work out whether a cheaper pump saves money

A pump that is 3p per litre cheaper saves £1.50 on a 50-litre fill. Whether that is a worthwhile saving depends on how far you drive to reach it. Check the local pump prices, calculate the difference for the amount you need, then account for any extra journey.

The Department for Energy Security and Net Zero publishes weekly UK petrol and diesel averages. They provide a national benchmark, but the figures available do not establish the latest publication date or the latest prices. Check the dated release before using an average as a current comparison. An individual forecourt may charge more or less than the national figure.

Turn a price difference into a fill-up cost

To compare two pumps, subtract the cheaper price per litre from the dearer one and multiply by the number of litres you expect to buy. Keep both prices in pence for the calculation, then divide the result by 100 to get pounds.

For example, illustrative prices only: suppose one station charges 145p per litre for petrol and another charges 142p. The difference is 3p per litre. Buying 50 litres would cost £72.50 at the first station and £71 at the second, a saving of £1.50. These are examples for the calculation, not reported UK prices.

The number of litres matters as much as the price gap. A driver buying 20 litres would save 60p from the same 3p difference. A driver buying 60 litres would save £1.80. Use the amount you actually need rather than assuming every visit is a full tank.

Check whether the detour uses up the saving

A cheaper pump can cost more overall if reaching it adds enough miles. Estimate the extra distance for the whole detour, including the return to your normal route. Then multiply those miles by your car’s fuel cost per mile. You can estimate that cost from your own fuel economy and the price you expect to pay.

Here is a second illustrative calculation. If the cheaper station saves £1.50 on your fill, but a detour adds 10 miles and your car uses 15p of fuel per mile, the extra driving costs about £1.50 in fuel. The pump saving has disappeared before allowing for your time or any other driving costs. If the cheaper station lies on a journey you were making anyway, the extra distance may be close to zero.

Traffic, cold starts and driving conditions can change fuel use, so treat a mileage calculation as an estimate. If two stations have nearly identical total costs, convenience may settle the choice.

Use the national average as a benchmark, not a local quote

The government’s weekly figures show average petrol and diesel prices across the UK for a stated period. They do not guarantee what a particular station charges today. Local prices can differ between nearby forecourts, and a displayed price may change after a weekly release.

When checking the latest government release, note its publication date and the period its prices cover. Compare the petrol average only with petrol pumps, or the diesel average only with diesel pumps. Then use the prices currently displayed by the stations you could realistically visit to make the final calculation.

Before setting off solely for cheaper fuel, check the station’s current price if available, work out the saving for the litres you need and compare it with the cost of the extra miles.

Source: Department for Energy Security and Net Zero