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Fuel Cost Calculator

What is my MPG?

Work out what a trip will cost in fuel, or what MPG you really got.

One Click Answers · Fuel Cost Calculator
oneclickanswers.com/fuel-cost-calculator · Printed
About this tool & how to use it

What it does

Works out the fuel cost and cost per mile of a trip from the miles, MPG and price, or your real MPG and cost per mile from a fill-up.

How to use it

  1. Choose whether you want the fuel cost of a trip or your MPG from a fill-up.
  2. Enter the miles, the MPG (or the gallons you added) and the price per gallon.
  3. Read the cost, the cost per mile and per 100 miles, and the litres-per-100-km equivalent.

The trip distance one way, or the miles driven since your last fill-up.

One click answer

Your answer will appear here.

Fill in the form and your answer appears here as you type.

Assumptions

  • Real mileage changes with speed, load, weather and traffic, so a trip cost is an estimate.
  • The numbers are fuel only: no payment, insurance, tolls or maintenance.
  • MPG from a fill-up is most accurate when you fill the tank to the same point both times.

Printed from oneclickanswers.com. Results are estimates based on what was entered; see the assumptions above.

How it works

Gallons are the miles divided by the MPG: 300 / 30 = 10 gallons. The cost is the gallons times the price: 10 x $3.50 = $35.00. This is the same fuel formula as the Trip Cost Estimator.

Cost per mile is the fuel cost divided by the miles: $35.00 / 300 is 11.7 cents. Per 100 miles it is $11.67.

For a fill-up, MPG is the miles driven divided by the gallons added to fill the tank again: 280 miles on 10 gallons is 28 MPG. Litres per 100 km is 235.2146 divided by the MPG, from 3.785411784 litres in a gallon and 1.609344 km in a mile.

Assumptions

  • Real mileage changes with speed, load, weather and traffic, so a trip cost is an estimate.
  • The numbers are fuel only: no payment, insurance, tolls or maintenance.
  • MPG from a fill-up is most accurate when you fill the tank to the same point both times.

Example

Input: 300 miles at 30 MPG, $3.50 a gallon

Result: Your trip will cost about $35.00 in gas. You would drive 300 miles and use about 10.00 gallons at 30.0 MPG and $3.50 a gallon (11.7 cents a mile, $11.67 per 100 miles, 7.8 litres per 100 km).

Questions

How do I calculate my MPG?

Fill the tank, note the miles, drive, then fill it again. Divide the miles driven by the gallons added. 280 miles on 10 gallons is 28 MPG.

How is the cost per mile worked out?

The fuel cost divided by the miles. $35.00 for 300 miles is about 11.7 cents a mile.

Does this include the cost of owning the car?

No, fuel only. The True Car Cost Calculator adds the payment, insurance, maintenance and fees.

Last reviewed 2026-10-04.

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