Fuel Cost Calculator
Calculate how much fuel a journey will use and how much it will cost. Enter the distance, fuel price and your vehicle’s fuel economy using UK MPG, US MPG, miles per litre, kilometres per litre or litres per 100 km. You can also include return trips, extra driving, passengers, parking and toll costs.
Calculate fuel cost
Use this for commute planning, long trips, comparing cars, estimating fuel for work mileage or splitting a journey cost between passengers. The result is an estimate because fuel price and real-world fuel economy can change.
Quick examples
| Total distance | — |
| Fuel economy used | — |
| Fuel price used | — |
| Cost per mile | — |
| Cost per kilometre | — |
How it works
The calculator converts the journey distance into miles and kilometres, then converts the selected fuel economy into litres used. It multiplies the estimated litres by your fuel price per litre. Return trips double the base distance, extra driving is added afterwards, and parking or toll costs are added to the final total.
Formula used
fuel used = total distance ÷ fuel economy
fuel cost = litres used × price per litre
total trip cost = fuel cost + parking/tolls/other costs
cost per person = total trip cost ÷ number of people
For MPG, the calculator converts gallons into litres. UK MPG uses 4.54609 litres per gallon, while US MPG uses 3.785411784 litres per gallon.
Worked example
Example: 100 miles at 45 UK MPG with fuel at 145p/L
litres used = 2.222 × 4.54609 = 10.102 L
fuel cost = 10.102 × £1.45 = £14.65
So, a 100-mile journey at 45 UK MPG with fuel at 145p per litre costs about £14.65 in fuel.
Common mistakes
Mixing UK MPG and US MPG
UK gallons and US gallons are different sizes, so UK MPG and US MPG are not the same.
Using dashboard MPG blindly
Dashboard fuel economy can be optimistic. Real-world fuel use changes with traffic, weather, tyre pressure and load.
Forgetting return trips
A journey might look cheap one way, but doubling it for the return can change the decision.
Ignoring extras
Parking, tolls, congestion charges and detours can be a large part of the real trip cost.
Common questions
How do I calculate fuel cost for a journey?⌄
Should I use UK MPG or US MPG?⌄
Why is my real fuel cost different?⌄
Can I split the fuel cost between passengers?⌄
Sources, assumptions and disclaimer
This calculator is for general journey planning and cost estimation. It uses the fuel economy and fuel price you enter. It does not fetch live fuel prices, predict traffic, account for every driving condition, or guarantee actual fuel consumption.
- Fuel price: use the price displayed at the pump or your best estimate.
- Fuel economy: real MPG can differ from manufacturer figures and dashboard readings.
- UK versus US MPG: the calculator separates UK and US MPG because UK and US gallons are different sizes.
- Extra costs: tolls, parking, congestion charges and other expenses are added after fuel cost.
- Disclaimer: this is an estimate only and should not be used as financial, legal, tax, fleet-management or safety-critical advice.