Petrol journey cost
Work out the fuel cost of a petrol journey from the distance, your car's fuel economy and the price at the pump.
Result
Fuel used
Cost
How to use this tool
- Enter the journey distance in miles.
- Enter your car's fuel economy in mpg (UK gallons) — check your dashboard's real-world average if available.
- Enter the pump price per litre you want to use.
- Read the fuel used and total cost.
Assumptions
- Uses UK imperial gallons (4.54609 litres), not US gallons.
- Uses the petrol price you enter; it does not fetch live pump prices.
- Real-world fuel economy varies with route, load, weather and driving style, and is often lower than an official test figure.
Sources & reference data
Technical details: what the fields mean
- Journey distance
distanceMiles - Total journey distance, in miles.
- Fuel economy
mpg - Miles per UK gallon — use your car's real-world average rather than the official spec figure for accuracy.
- Petrol price
pricePerLitre - Petrol price you entered, in pounds per litre; no live price feed is used.
Methodology
Litres used = (distance ÷ mpg) × 4.54609 (litres per UK gallon). Cost = litres used × price per litre.
Worked example
Illustrative 200-mile journey (the fuel price is an example, not a current market quote)
Inputs: Journey distance: 200 miles, Fuel economy: 45 mpg, Petrol price: £1.45/L
Result: Fuel used = (200 miles ÷ 45 mpg) × 4.54609 = 20.2048 L (displayed as 20.2 L). Cost = 20.2048 L × £1.45/L = £29.30. The price is illustrative, not a live pump quote.
Practical guidance
- To compare two routes for the same car, run each distance with the same real-world mpg and pump price, then compare the fuel used and cost.
- Compare to the diesel journey cost calculator if you're deciding between fuel types for a specific journey pattern.
Common mistakes
- Entering pence (145) instead of pounds (£1.45) for the price-per-litre field.
- Comparing journeys with different MPG or pump-price inputs as if only the route changed.
FAQs
Should I use official or real-world mpg?
Use a trip-computer or fuel-record average for your own journey budget. An official test figure is more useful when comparing vehicles under the same test procedure, but it may not match your route or driving conditions.
Last reviewed: 2026-10-11
This is an estimate from your distance, MPG and pump-price inputs; tolls, parking, servicing, insurance and vehicle purchase cost are outside its scope.
This tool provides an indicative estimate, based on the assumptions stated above.
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