Trip Fuel Cost Calculator

Direct answer

Divide route miles by miles per gallon to estimate gallons, then multiply by the fuel price per gallon. The U.S. Department of Energy Alternative Fuels Data Center documents the same distance-divided-by-MPG relationship for conventional fuel use and separates fuel volume from its unit price.

Variables and formula

• Trip distance: planned route miles.
• Vehicle efficiency: miles per gallon appropriate to the expected conditions.
• Fuel price: a price per gallon selected for this scenario.

Trip fuel cost = Trip distance / Miles per gallon * Fuel price per gallon

Reproducible example

For 300 miles, 30 mpg and $3.50 per gallon, 300 / 30 * 3.50 = $35.00. The estimated fuel volume is 10 gallons.

Interpretation

This is a route-level fuel scenario, not a guarantee of a fill-up total. Use a recent observed MPG for similar roads, load and weather when possible, then update the price immediately before travel.

Assumptions and limitations

• Distance, efficiency and price use miles and gallons for the same fuel type.
• Fuel economy is treated as constant for the trip.
• Tolls, parking, charging, maintenance and non-fuel travel costs are excluded.

Common mistakes

• Multiplying miles by MPG instead of dividing.
• Using a combined rating for a route with very different conditions.
• Treating fuel cost as the full cost of a journey.

Assumptions

• Distance, fuel economy and price use miles, gallons and the same fuel type.
• The entered miles per gallon is suitable for the route, load, weather and driving conditions.
• Parking, tolls, charging, maintenance and other travel costs are excluded.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• Vehicle Cost Calculator Assumptions and Methodology; U.S. Department of Energy Alternative Fuels Data Center; accessed Aug 9, 2026