Our Calculator

Fuel Cost Calculator

Estimate a trip's gas cost using distance in miles, fuel economy in US MPG and price per US gallon. See gallons needed and the cost per mile.

No signup requiredMethod and rounding explainedEditorial standards and sources

Enter trip and fuel details

Use expected trip miles, realistic vehicle fuel economy, and the gas price you expect to pay.

miles
MPG
$/gallon
Your result

Estimated trip fuel cost

Updates automatically as you change the inputs.

Estimated fuel cost
$37.50
Fuel needed10.71 gal
Trip distance300 mi
Cost per mile$0.125

How to use the fuel cost calculator

Enter the miles you expect to drive, the vehicle's realistic miles per gallon, and gas price per gallon. The calculator divides distance by MPG to estimate gallons, then multiplies by price.

Trip fuel cost formula

Calculation formulaTrip fuel cost formula
Used for the result above
Gallons needed = miles ÷ MPG. Fuel cost = gallons needed × price per gallon.

Real fuel economy can change with speed, weather, traffic, elevation, tire pressure, idling, and vehicle load.

Example: Hannah budgets for a road trip

Hannah plans a 300-mile trip in a car averaging 30 miles per US gallon. The trip needs approximately 300 ÷ 30 = 10 gallons. At $3.50 a gallon, the estimated fuel cost is $35.

For a return trip of the same distance, enter 600 miles. Parking, tolls, maintenance, and differences in traffic or driving conditions are separate from the fuel estimate.

Use US gallons throughout the estimate

A 300-mile trip at 30 MPG uses 10 US gallons. At $3.50 per gallon, the estimated fuel cost is $35.

Enter the total distance you plan to drive, including the return trip if needed. Traffic, load, weather and idling can change actual fuel use.

Split a round-trip fuel budget

For a 300-mile round trip at 30 miles per US gallon, the vehicle uses about 10 gallons. At $3.50 per gallon, the fuel estimate is $35. Dividing that cost among three travelers gives about $11.67 each.

Enter the total miles you expect to drive, including the return journey and detours. Parking, tolls, rental charges and maintenance are separate costs. Do not mix imperial-gallon MPG with a US-gallon fuel price.

Assumptions and limitations

What the estimate assumes

Tolls, parking, charging, maintenance, and other vehicle costs are not included.

Fuel Cost Calculator FAQs

Should I use highway or combined MPG?

Use the fuel economy that best matches the trip. Combined MPG is a reasonable starting point for mixed driving.

Does the calculator include a return trip?

Only if your entered mileage includes it.

What if gas prices change during the trip?

Use an average expected price or run separate calculations for different legs.

Does this calculate EV charging cost?

No. This tool is based on miles per gallon and gasoline price.

Fuel-cost estimate only. Real mileage and gas prices vary with driving conditions, vehicle condition, and location.