How do I use the fuel calculator?
Enter the distance you're travelling, your vehicle's fuel economy, and the price of fuel, choosing whichever units you're most comfortable with. The amount of fuel you'll use and the estimated cost update instantly as you type.
How do I work out the cost of petrol or diesel for a journey?
Divide the distance by your miles per gallon (MPG) to get the gallons you need. Multiply by 4.546 to turn UK gallons into litres, then multiply by the price per litre. For example, 200 miles at 40 MPG needs 5 gallons, which is 22.7 litres. At £1.45 a litre, that costs about £33.
How do I work out the fuel cost per mile?
Multiply the price per litre by 4.546, then divide by your MPG. At £1.45 a litre and 40 MPG, that is 1.45 × 4.546 ÷ 40, which is about 16.5p per mile. Enter a distance of 1 mile in the calculator to see the same figure.
What fuel price should I use?
Use the price you expect to pay. The calculator starts with the current UK average for the fuel you pick, taken from the official GOV.UK Fuel Finder scheme. Type your own price to replace it. To use a local price instead, choose "Find the cheapest station near me" and enter a postcode or town, or share your location. The calculator then fills in the cheapest price within 10 miles. Only prices updated in the last 7 days count.
The fuel price map shows every station near you or along your route. It lists prices in pence per litre, so divide by 100 before you enter one here: 145.9p is 1.459 per litre.
Is the cheapest station worth the drive?
Not always. The calculator shows how far away the station is, but it does not add the cost of the trip there. A few pence a litre can disappear in the extra miles, so check the distance against the saving.
What's the difference between a UK and US gallon?
A UK (imperial) gallon is about 4.546 litres, while a US gallon is smaller, at about 3.785 litres. This means the same car will show a higher 'miles per gallon' figure when measured in UK gallons than in US gallons, even though nothing about the car has changed – so it's worth double-checking which one a figure you've read elsewhere is using.
Where do I find my car's fuel economy?
Most manufacturers publish an official fuel economy figure, but real-world driving (traffic, terrain, load and driving style) usually gives a lower number. If you know roughly how many miles or kilometres you get from a full tank, you can work backwards to estimate your own figure and get a more accurate result.
Is this calculation exact?
It's a close estimate based on the figures you provide. Actual fuel use varies with traffic, weather, road type, driving style, and how much you're carrying, so treat the result as a helpful guide rather than an exact prediction.
Can I work fuel costs into a wider budget?
Yes – once you know roughly what a regular trip costs, log it as a recurring outgoing in the income and bills tracker to see how it fits alongside your other monthly spending.