Current Average Price
Based on data from 30/03/2026
Petrol prices can be influenced by various factors. One of the primary drivers is the global crude oil market. Fluctuations in crude oil prices, which can be influenced by geopolitical events and supply and demand dynamics, can impact the cost of petrol at the pump. Additionally, government taxes and levies, such as fuel duty and VAT, also contribute to the final price consumers pay for petrol.
Petrol in the UK is sold by the litre at the pump, so to find the price per gallon you simply multiply the pence-per-litre price by the number of litres in a UK Imperial gallon — which is 4.54609 litres. So if petrol costs 140p per litre, a gallon costs roughly £6.36.
It's worth noting that the US gallon is smaller (3.785 litres), so petrol prices quoted "per gallon" from American sources will always look cheaper than UK equivalents — even before accounting for currency differences.
The retail price of petrol in the UK is made up of several components:
Tax alone (fuel duty + VAT) accounts for well over half the price you pay at the pump, which is why UK petrol prices are significantly higher than in countries with lower fuel taxation.
Knowing the current petrol price per gallon makes it straightforward to calculate how much each journey is costing you. If your car returns 40 MPG and petrol costs around £6.30 per gallon, every 40 miles of driving costs you roughly £6.30. That's about 15.75p per mile.
You can use our free MPG calculator to work out your exact cost per mile based on your car's real-world fuel consumption and today's fuel prices.
Even within the same town, petrol prices can vary by 5-10p per litre between different forecourts. Supermarket petrol stations (Tesco, Asda, Sainsbury's, Morrisons) are typically the cheapest, often undercutting motorway services and branded forecourts by a significant margin. Motorway service stations consistently charge the most, partly due to their captive audience and higher operating costs.
Regional variation also plays a role — rural areas and remote locations often see higher prices due to additional transportation costs. You can track weekly average UK petrol prices on our fuel prices page.
Diesel is typically a few pence per litre more expensive than petrol at UK forecourts, which means it costs more per gallon. However, diesel engines are generally more fuel efficient — a diesel car will often travel further on each gallon than a comparable petrol model. Whether petrol or diesel works out cheaper overall depends on your annual mileage and driving style. See our diesel per gallon guide for a direct comparison.