Free calculator
How much does it cost to fill my tank?
Enter your tank size and postcode district, and see what a full tank costs at the cheapest forecourt near you today versus the dearest, and how much the difference is worth.
Prices prefilled from the official Fuel Finder data, updated 28 August 2026. Change any box and the answer updates as you type.
The number on the pump is only half the story
Knowing that petrol is about 162p a litre tells you roughly what a tank costs. Knowing that the forecourt two miles away is 8p cheaper than the one on your street tells you what you are actually losing every time you fill up on autopilot. That is why this calculator asks for your postcode district. It reads the live prices for every forecourt within five miles, the same data as the search on the home page, and shows the real spread near you.
Most cars have a tank between 40 and 60 litres. Small hatchbacks sit around 40 to 45, family cars around 50 to 55 and larger cars and SUVs 60 to 70. If you are not sure, the handbook will say, and 55 litres is a fair middle guess.
Turning the saving into a habit
The gap between the cheapest and dearest forecourt in a typical town is often several pence a litre, which on a 55 litre tank is a few pounds every fill and well over a hundred pounds a year. Use the price finder to see exactly which forecourt is cheapest right now, or set a free alert so you hear when the price near you drops.
Common questions
How much does it cost to fill a tank of petrol?
At today's typical UK price a 55 litre tank costs around 89 pounds, but the real figure depends on your local forecourt. Enter your postcode district above and the calculator uses the live prices near you to show the cheapest and dearest.
How big is my fuel tank?
Most small cars hold 40 to 45 litres, family cars 50 to 55, and larger cars and SUVs 60 to 70. Your handbook gives the exact figure. If you are unsure, 55 litres is a reasonable estimate.
Where do the local prices come from?
From the official Fuel Finder open data, which every forecourt must update within 30 minutes of a price change, refreshed on this site twice a day. The calculator looks at every forecourt within five miles of your postcode district.