Journey Fuel Cost Calculator

Work out exactly how much fuel your next trip will cost. Enter the distance in miles, your real-world MPG and the current fuel price per litre. For the most accurate result, use our MPG calculator to measure your true fuel economy rather than relying on the manufacturer's figure.

Need the current fuel price? Use our fuel station finder to see live prices near your start or end point, updated every 30 minutes.

Calculate the cost of a journey based on distance, MPG and fuel price

How to calculate the fuel cost of a journey

The formula converts your distance and fuel economy into a cost:

Cost (£) = (distance in miles ÷ MPG) × 4.54609 × price per litre ÷ 100

Breaking that down: divide miles by MPG to get imperial gallons used, multiply by 4.54609 to convert to litres, then multiply by the pence-per-litre price and divide by 100 to get pounds.

Worked example: A 200-mile trip in a car doing 38 MPG with petrol at 142p per litre: 200 ÷ 38 = 5.26 gallons = 23.93 litres. 23.93 × 142p = 3,398p = £33.98.

Tips to reduce the cost of a long journey

  • Fill up before the motorway — service station fuel is typically 10–15p per litre more expensive than supermarket forecourts. Plan a fill-up near your start point.
  • Cruise at 60 mph, not 70 — aerodynamic drag rises with the square of speed. Dropping from 70 to 60 mph can improve fuel economy by 10–15%.
  • Check tyre pressures — underinflated tyres increase rolling resistance. On a 300-mile trip, correct pressures can save £3–5 in fuel.
  • Remove roof racks and boxes — a roof box at motorway speed adds roughly 15% to fuel consumption.
  • Use cruise control on flat roads — maintaining a steady speed is more efficient than constantly accelerating and braking.
  • Share the journey — splitting fuel costs between passengers halves or quarters the per-person cost instantly.

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Frequently Asked Questions

Divide the journey distance (in miles) by your MPG to get gallons used. Multiply by 4.546 to convert to litres, then multiply by the fuel price in pence per litre and divide by 100 to get the cost in pounds. This calculator does all of that for you.

It depends on your MPG and the current fuel price. A car doing 30 MPG uses about a third more fuel than one doing 40 MPG over the same distance. Enter your figures into the calculator above for an accurate, up-to-date result based on today's fuel prices.

Always use your real-world MPG for the most accurate result. Manufacturer figures are typically 20–30% higher than what you'll achieve in normal driving. Use our MPG Calculator to measure your true fuel economy.

Steady motorway cruising at 60 mph is often more efficient than stop-start urban driving. However, speeds above 70 mph increase fuel consumption sharply due to aerodynamic drag. Every 10 mph above 60 costs roughly 10–15% more fuel.

Use our fuel station finder to see live prices at stations near you, updated every 30 minutes from the UK government's Fuel Finder data.

Fill up before the motorway — service station fuel is typically 10–15p per litre more expensive. Drive at 60 mph rather than 70 mph to save 10–15% on fuel. Check tyre pressures before setting off, and remove roof racks or boxes if not needed.

Yes for diesel — enter your diesel MPG and the diesel price per litre. For electric cars, fuel cost works differently (pence per kWh rather than per litre). Use our car comparison calculator to compare running costs between petrol, diesel and electric vehicles.