Fuel Cost Calculator
Estimate how much fuel a trip will use and what it will cost, in US (mpg / $ per gallon) or metric (L/100km / price per liter) units.
Trip details
Total distance:
Fuel needed:
Total fuel cost:
Cost per mile / km:
US vs. metric fuel efficiency
US fuel efficiency (mpg) is expressed as distance per unit of fuel — a higher number means better efficiency. Metric fuel efficiency (L/100km) is inverted: it's fuel used per fixed distance — a lower number means better efficiency. This inversion is why the calculator uses a different formula for each unit system rather than a simple conversion factor.
Frequently asked questions
Why does round-trip cost more than double a one-way estimate might suggest? It doesn't — round trip simply doubles the one-way distance before calculating, so the fuel and cost scale linearly with total distance traveled either way.
Does this account for highway vs. city driving differences? No — enter the fuel efficiency figure that best matches your expected driving conditions (many vehicles list separate city and highway mpg/L-per-100km ratings) for a more accurate estimate.
Why might my actual fuel cost differ from this estimate? Real-world factors like driving style, terrain, vehicle load, tire pressure, and traffic conditions can meaningfully change actual fuel consumption compared to a rated or assumed efficiency figure.