Free calculator
Fuel Cost Calculator
Estimate fuel cost for a trip from distance, MPG and gasoline price.
Formula distance ÷ MPG × gasoline price
Calculate gas cost for a trip
Enter the total trip distance, expected MPG and gasoline price per US gallon. Distance divided by MPG gives gallons used; multiplying by the pump price gives trip fuel cost. Use the total distance for a round trip, not just the distance to your destination.
Worked example
For a 300-mile trip at 30 mpg and $3.50 per gallon: 300 ÷ 30 = 10 gallons, then 10 × $3.50 = $35. A 600-mile round trip with the same inputs costs $70 in fuel.
How to use the result
This estimates fuel only. Add tolls, parking and other travel expenses separately. For a mixed route, use a realistic combined MPG figure or your measured fuel economy rather than assuming the highway rating for the entire trip.
Sources and assumptions
U.S. EIA public gasoline price table Accessed 2026-09-05Calculation methodology. Worked examples use the expressly stated inputs; sample prices are illustrative rather than local quotes.
Use a vehicle service sheet next
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Frequently asked questions
How do I calculate fuel cost for a round trip?
Enter the combined outward and return distance. If both legs are 150 miles, enter 300 miles. The calculator does not automatically double your distance.
Should I use city or highway MPG?
Use the rating that best describes the route, or your measured average MPG. A mixed city/highway trip usually needs a combined estimate.
Does this calculator use US or Imperial gallons?
The inputs use miles per US gallon and dollars per US gallon. Convert Imperial MPG before using it with a US pump price.
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