How do I calculate gas cost for a trip?

Divide trip miles by MPG to get gallons needed, then multiply by the gas price per gallon. For example, 300 miles at 30 MPG uses 10 gallons; at $3.50 per gallon, the fuel cost is $35.

Does this use US gallons?

Yes. The calculator is set up for the common U.S. trip-planning intent: miles, US gallons, MPG and dollars per gallon.

Why can real fuel cost differ?

Actual fuel use changes with driving style, traffic, speed, weather, tire pressure, load and the exact route. Treat the result as a planning estimate.

Fuel Cost Calculator

Estimate gas cost for a trip from distance, vehicle MPG and price per gallon, with gallons needed and cost per mile.

Calculation mode

Distance (mi)

Fuel economy (mpg)

Gas price ($/gal)

Estimate Gas Cost for a Trip

English fuel-cost searches usually expect a quick road-trip calculator: distance in miles, fuel economy in MPG and gas price per gallon. The result shows estimated gallons, total cost and cost per mile so the trip can be compared with other travel or commuting options.

Use your real MPG

EPA label MPG is a useful starting point, but traffic, weather, speed, tires, load and terrain can change real-world fuel economy.

Fuel Cost Formula

g a l l o n s = \frac{mi l es}{M P G}

t r i p cos t = g a l l o n s \times p r i ce p er g a l l o n

cos t p er mi l e = \frac{p r i ce p er g a l l o n}{M P G}

When the Estimate Can Change

Use current local gas prices rather than national averages for budgeting.
Use city or highway MPG depending on the actual route.
Add a margin for idling, detours, mountain roads, cold weather and heavy cargo.
For international trips, convert between US MPG and L/100 km before comparing vehicles.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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