Trip Fuel Cost Calculator

Q: How do I split gas money fairly?

Enter everyone who should share the cost in People sharing the cost , including the driver if they pay too. The tool divides the trip cost equally. For uneven shares or other expenses, the trip cost splitter handles who paid what.

Q: Does a round trip simply double the cost?

Yes. Round trip there and back doubles the distance, and fuel cost is proportional to distance, so the cost doubles too.

Calculate the fuel cost of a road trip from the distance, your L/100 km or mpg and the fuel price, split it per person and compare vehicles.

Trip

Distance

Trip type

People sharing the cost

Fuel price

Any currency: the results use the currency of the price you type.

Vehicles to compare

Enter the fuel economy of each vehicle in any unit: L/100 km, km/L, mpg (US), mpg (UK) or gal/100 mi.

Total distance: –
Fuel needed: –
Trip cost: –
Cost per person: –

Comparison

Vehicle	Economy	Fuel	Trip cost	Per person	Per 100 km	Per mile	vs cheapest

Estimate only: real consumption depends on speed, traffic, load, weather, air conditioning and tire pressure. Tolls, parking and wear are not included.

How to use the trip fuel cost calculator

Enter the Distance of the trip and choose km or miles.
Pick the Trip type: One way, or Round trip (there and back) to double the distance.
Enter the number of People sharing the cost. Count the driver if they pay a share.
Type the Fuel price and say whether it is per litre, per US gallon or per imperial gallon. Any currency works: the results use the currency of the price you type.
Under Vehicles to compare, give each vehicle a Name (optional) and its Fuel economy in the unit you know: L/100 km, km/L, mpg (US), mpg (UK) or gal/100 mi. Use Add a vehicle to compare up to six, and × to remove one.

The tool shows the Total distance, the Fuel needed, the Trip cost and the Cost per person for the first vehicle, a Comparison table when you enter two or more vehicles, and the calculation step by step. Everything runs in your browser.

How the fuel cost is calculated

Every fuel economy is first converted to litres per 100 km, the fuel-per-distance measure. Then:

Fuel (L) = distance (km) × L/100 km ÷ 100
Price per litre = price per gallon ÷ 3.785411784 (US gallon) or ÷ 4.54609 (imperial gallon)
Trip cost = fuel (L) × price per litre
Cost per person = trip cost ÷ number of people

The conversions to L/100 km use exact definitions: L/100 km = 235.215 ÷ mpg (US), 282.481 ÷ mpg (UK) and 100 ÷ km/L. One mile is exactly 1.609344 km.

Metric example. A 250 km drive there and back is 500 km. A compact car using 6.5 L/100 km burns 500 × 6.5 ÷ 100 = 32.5 L. At 1.65 per litre that is 53.63, or 26.81 each for two people. An SUV at 10 L/100 km needs 50 L and costs 82.50, so 28.88 more than the car.

Imperial example. A 100 mile one-way trip in a car rated 25 mpg (US) uses 100 ÷ 25 = 4 US gallons. At 3.50 per gallon, the trip costs 14.00.

Comparing vehicles

The comparison table lists, for each vehicle, its fuel economy as typed, the fuel in litres and US gallons, the trip cost, the cost per person, the cost per 100 km, the cost per mile and how much more it costs than the cheapest one. It is a quick way to decide whether to take the small car or the van, or to see what a more efficient car would save on a regular commute. For an electric car, use the EV charging cost calculator, which compares with gasoline.

Tips for a realistic estimate

Use your real consumption from the trip computer or a full-tank calculation (litres added ÷ km driven × 100), not the official label: WLTP and EPA test figures are often 10 to 25 % optimistic.
Highway driving above 110 km/h (70 mph), a roof box, a trailer, cold weather and air conditioning all raise consumption.
The result covers fuel only. Tolls, parking, ferries, insurance and wear on the car are extra.

Frequently asked questions

How do I split gas money fairly?

Enter everyone who should share the cost in People sharing the cost, including the driver if they pay too. The tool divides the trip cost equally. For uneven shares or other expenses, the trip cost splitter handles who paid what.

Does a round trip simply double the cost?

Yes. Round trip (there and back) doubles the distance, and fuel cost is proportional to distance, so the cost doubles too.

My car shows km/L or mpg. Which unit should I choose?

Choose the unit your car or its manual shows. The tool converts it to L/100 km internally, so all units give the same result for the same car.

Is a US gallon the same as an imperial gallon?

No. A US gallon is 3.785 L and an imperial gallon is 4.546 L, about 20 % more. Pick the right one for both the fuel economy (mpg US or mpg UK) and the price.

Why is my real fuel bill different?

The result is an estimate. Traffic, speed, hills, load, tire pressure and weather change consumption, and fuel prices vary from one station to the next.