ABritish forecourt hasn’t legally quoted a gallon price since October 1995. But drivers still think in gallons, budget in gallons, and complain in gallons — and the question “how much is a gallon of petrol?” still gets typed into Google thousands of times a month. Here’s the 2026 answer.
Today’s number
An imperial (UK) gallon is 4.54609 litres. Multiply that by the current pence-per-litre pump price and you get the gallon price. At a UK national average around 156p per litre for E10 unleaded, a UK gallon costs about £7.09. Diesel at 187p/L works out to roughly £8.50 per gallon.
For the live figure — the number moves every five minutes — see the FuelHawk fuel price index. Multiply whatever the E10 average reads by 4.546 and that’s your UK gallon.
Why it matters that it’s the UK gallon
The US gallon is 3.78541 litres — smaller by almost 17%. American websites and spec sheets use that figure by default. If you read “UK petrol is £8 a gallon” on a US news site, they might mean a US gallon (£5.90 per UK gallon equivalent) or a UK one. The two can’t be reconciled without knowing which.
When anyone in Britain says “a gallon of petrol” they almost certainly mean imperial — the measurement drilled into drivers who passed their tests before 1995 and the one modern mpg ratings still use.
A longer timeline
Petrol hit £1 per UK gallon in 1973. £2 in 1980. £3 in 2005. £5 in 2011. By early 2022 — the pre-Russian-invasion peak — the UK average was hovering around £6.50 per gallon. The 2022 supply shock briefly pushed it over £8.50; the 5p duty cut and easing wholesale brought it back. At today’s 156p/L it’s about £7.09, roughly where real prices were in the mid-2010s once you adjust for inflation.
Fuel duty does most of the heavy lifting on the total. The flat 52.95p per litre hasn’t moved since 2011, and the 5p cut introduced in 2022 is still in place. That puts about £2.41 of duty into every UK gallon, before you add VAT on top — which in turn puts about £1.18 more per gallon into the Exchequer. Tax alone accounts for roughly half the pump price.
What a gallon buys elsewhere
Translated to sterling, the typical gallon price in April 2026 works out roughly:
- UK: £7.09 per imperial gallon
- Republic of Ireland: £7.24 per imperial gallon
- Germany: £7.45 per imperial gallon
- France: £7.80 per imperial gallon
- United States: roughly £2.80 per US gallon, or £3.38 scaled to a UK gallon
Britain sits mid-table for Western Europe, comfortably cheaper than the Netherlands or Italy, and roughly twice what Americans pay — almost all of that gap being tax rather than underlying wholesale cost.
The one-line answer
About £7.10 per gallon of unleaded, £8.50 per gallon of diesel, and moving with wholesale prices every day. The exact number lives on the index page below — or look up your own local forecourt by postcode and multiply the per-litre number you see by 4.546.
Today’s live UK national average →
The cheapest unleaded petrol right now →
Find the cheapest fuel near you by postcode →