Fuel Cost Calculator
Enter your journey distance and fuel economy to find out how much your trip will cost in fuel, with weekly, monthly, and annual estimates.
How much will your journey cost in fuel? Whether you are planning a daily commute, a school run, or a road trip, this calculator gives you an accurate fuel cost estimate based on your vehicle's fuel economy and current fuel prices.
You can also compare driving costs against public transport to see which option saves you more.
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What this calculator does
This calculator estimates the fuel cost for any journey based on the distance, your vehicle’s fuel economy (MPG or litres/100km), and the price of fuel per litre. It supports return trips, cost splitting between passengers, and comparison with public transport.
Who it is for
Drivers planning journeys, commuters comparing driving vs public transport, families budgeting travel costs, or anyone wanting to understand their fuel expenses.
How to use it
Enter your journey distance, fuel economy, and current fuel price. Select whether it is a return trip. Optionally add trips per week for ongoing cost estimates, or enter a public transport cost to compare.
How the calculation works
We convert your fuel economy to litres per 100km, calculate the litres needed for your journey distance, and multiply by the fuel price per litre. For return trips, the distance is doubled. Weekly, monthly, and annual costs are calculated from your trips-per-week input.
Worked example
A 30-mile one-way commute at 40 MPG with fuel at £1.40/litre: Distance in km = 48.3km. Litres needed = 48.3 × (4.546 / 40 / 1.609) = 5.46 litres. Cost = 5.46 × £1.40 = £7.65. Return trip = £15.30. Five times per week = £76.50/week (£3,978/year).
Assumptions and limitations
- Fuel economy is assumed constant regardless of driving conditions
- MPG uses UK imperial gallons (4.546 litres), not US gallons
- Fuel prices change frequently — check local prices for accuracy
- Does not account for congestion, terrain, or driving style which affect real-world economy
- Monthly cost assumes 4.33 weeks per month
Frequently asked questions
How much does it cost to drive 100 miles?
At 40 MPG with fuel at £1.40/litre, 100 miles costs approximately £15.90 in fuel. Use this calculator with your actual MPG and fuel price for a personalised answer.
What is a good MPG for a car?
A modern petrol car typically achieves 35–50 MPG. Diesel cars often achieve 45–65 MPG. Hybrid cars can reach 60–80+ MPG in mixed driving.
Is it cheaper to drive or take the train?
It depends on the journey. Short urban trips are often cheaper by public transport. Longer motorway journeys with 2+ passengers are usually cheaper by car. Use the comparison feature in this calculator to find out.
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Sources and references
UK average fuel prices (https://www.gov.uk/government/statistics/weekly-road-fuel-prices), Imperial gallon conversion (4.54609 litres)
Last updated
Last reviewed: 2025-04-10.