Fuel cost calculator
Distance × fuel economy × price = trip cost. Split it across the carpool while you're here.
Fuel-economy units
Most of the world quotes fuel economy as L/100 km — lower is better. The US and UK use MPG — higher is better. The conversion is L/100 km = 235.215 ÷ MPG. (UK and US gallons differ; we use US gallons to match how MPG is most commonly cited on car spec sheets.)
Real-world vs sticker
Manufacturer-quoted fuel economy is measured on a standardised test cycle and is usually 10–20% optimistic compared to real driving — especially short trips, hilly routes, and motorway cruising. Punch in your actual recent average for a more honest number.
Frequently asked questions
How do I convert MPG to L/100 km?
Divide 235.215 by the MPG figure: L/100 km = 235.215 ÷ MPG. So 30 MPG is about 7.84 L/100 km. Lower L/100 km is better; higher MPG is better.
How do I split fuel costs for a road trip?
Total cost = (distance × fuel-economy × price). Divide that by the number of passengers to get the per-person share — the calculator's 'Split between' slider handles it for you.