Auto Tools

Gas Mileage Calculator

Estimate miles per gallon, trip fuel cost, and cost per mile from miles driven, gallons used, and fuel price.

Updated April 11, 2026
Free online tool
Planning and research use

Why this page exists

Fuel economy is easier to understand when you can connect MPG to the actual cost of a trip or a tank. This calculator helps you do both at once by turning miles driven, gallons used, and fuel price into a quick fuel-efficiency snapshot.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Gas mileage calculator

Estimate MPG, total fuel cost, and cost per mile from miles driven, gallons used, and fuel price.

Result

30.00 MPG

Estimated fuel efficiency and fuel cost based on the trip or tank numbers you entered.

Miles per gallon30.00 MPG

Estimated fuel cost$43.16

Estimated cost per mile$0.14

Gallons used10.40 gallons

At 30.00 MPG, every gallon covered about 30.00 miles in this estimate.
Use this result to compare vehicles, driving habits, or route changes when you want a simple fuel-efficiency snapshot.
If you fill up in different areas, rerun the fuel cost with local gas prices to see how much the trip or tank total changes.

Actual fuel economy changes with traffic, temperature, terrain, speed, and vehicle condition. Use this as a quick planning estimate.

Planning note

Last updated April 11, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter how many miles were driven and how many gallons of fuel were used.

Add the current fuel price per gallon if you want the estimate to include trip or tank cost too.

The calculator shows MPG, the total fuel cost for the numbers entered, and the estimated cost per mile.

Understanding your result

MPG explains how efficiently the vehicle used fuel, while cost per mile helps turn that efficiency into a budgeting number you can compare across trips, routes, or vehicles.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Check a recent fill-up

Use the odometer miles and gallons pumped to estimate MPG after a tank of driving.

Compare two vehicles

Run separate MPG estimates for two vehicles to see how much their operating cost differs per mile.

Track commute efficiency

Rerun the numbers after a route or schedule change to see whether traffic is dragging fuel economy down.

FAQ

Common questions

What is a good use for cost per mile?

Cost per mile is helpful when you want to compare the operating cost of different vehicles, routes, or driving habits in one simple number.

Why can MPG change from tank to tank?

Traffic, speed, weather, terrain, tire pressure, and vehicle load can all move fuel economy up or down from one tank to the next.

Can this help with commute budgeting?

Yes. If you use representative miles, gallons, and local fuel price, it becomes a quick way to estimate recurring driving cost.

Related tools

Keep comparing

Use these related tools to compare nearby scenarios, check a second estimate, or keep narrowing down the right decision.

Auto ToolsUpdated April 11, 2026