Fuel cost calculator
Work out trip fuel cost from distance, fuel economy and price: metric or imperial distance, liters, US or UK gallons, economy in L/100km, km/L or MPG, plus cost per kilometer and per passenger.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Trip details
Distance, economy and price all accept metric or imperial units: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L. Money is shown in the same currency as the price you enter.
Result
176.63
0.589
0.948
44.16
22.50 L · 5.94 US gal · 4.95 UK gal
300.00 km · 186.41 mi
7.50 L/100km · 31.36 MPG(US) · 37.66 MPG(UK) · 13.33 km/L
7.850 / L
What this tool does
- Budget a road trip before you leave: enter the distance, fuel economy and price to get the total fuel cost and the cost per kilometer.
- Split the bill between passengers — put the head count in and the tool returns each person’s share.
- Compare 7.5 L/100km with 30 MPG by switching the economy unit; both are converted to the same basis.
- Mix units freely: miles and US gallons for a rental car abroad, kilometers and liters back home.
Example
Input
Distance 300 km, economy 7.5 L/100km, price 7.85 per liter, 4 people in the car
Output
Total fuel cost 176.63, cost per kilometer 0.589, cost per person 44.16, fuel used 22.50 L (5.94 US gal), economy conversion 7.50 L/100km · 31.36 MPG(US) · 37.66 MPG(UK) · 13.33 km/L
All conversions use exact constants: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L.
Frequently asked questions
How different are US and UK gallons?
One US gallon is 3.785411784 L, one UK gallon is 4.54609 L — about 20% more. The same “40 MPG” figure therefore means better economy in the UK, so check which gallon the number on your dashboard uses.
How do MPG and L/100km convert?
Everything is normalised to L/100km internally: MPG(US) becomes 100 × 3.785411784 ÷ (MPG × 1.609344), and MPG(UK) uses 4.54609 instead. The relationship is inverse — higher MPG and lower L/100km both mean better economy.
Is this based on real-world fuel consumption?
No — it uses the economy figure you type in, so it is an estimate from the rated value. Traffic, load, tyre pressure and air conditioning typically push real consumption 10–20% above the rated number; use your own average for a realistic budget.
Why is there no currency symbol on the result?
You supply the fuel price, so the tool cannot know whether it is in dollars, euros or yuan. The cost is always in the same currency as the price you entered.
What happens if I enter an impossible distance or head count?
Distance must be between 0 and 40000 km and the number of people must be an integer from 1 to 99. Anything outside that range shows an error instead of a plausible-looking wrong number.
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