How it works
Efficiency is turned into the fuel needed for the distance, multiplied by the price, then tolls are added and the total split by the number of people. A round trip doubles fuel and tolls. For electric cars, the energy needed comes from kWh/100 km, km/kWh or mi/kWh and is multiplied by the price per kWh. US (3.785 L) and UK (4.546 L) gallons differ.
100 km at 8 L/100 km → 8 L × price + tolls ÷ people
Tips
- Find your car's real efficiency from the last few fill-ups, not the brochure — city driving is always thirstier.
- For regular commutes, set people to 1 and compare the per-km figure across cars.
- Everything runs in your browser; nothing is uploaded.
Standards and sources
- Unit conversions: US gallon 3.78541 L, UK gallon 4.54609 L, mile 1.609344 km
Last reviewed October 12, 2026
Frequently asked questions
What is the difference between US and UK MPG?
The gallons differ: a US gallon is 3.785 litres while a UK (imperial) gallon is 4.546 litres. The same MPG number therefore means different efficiency — pick the one your country uses.
How is the per-person share computed?
Fuel cost plus tolls, doubled for round trips, divided by the number of people. The driver pays an equal share unless you adjust afterwards.
Where do I find my real efficiency?
Divide litres filled by kilometres driven over several fill-ups. Brochure figures are measured in ideal conditions and city driving is always thirstier.
Which currency is used?
Yours. Enter the fuel price and tolls in your own currency and every result follows it.