How to Calculate Gas Mileage (MPG)

Gas mileage (MPG) measures how many miles your vehicle travels per gallon of fuel. Higher MPG means better fuel efficiency and lower costs.

The Formula

MPG = Miles Driven / Gallons Used

Where:

MilesMiles Driven — Distance traveled since last fill-up
GallonsGallons Used — Fuel consumed since last fill-up
MPGMiles Per Gallon — Your vehicle fuel efficiency

Step-by-Step Example

Here's how to calculate gas mileage (mpg) step by step:

  1. 1Fill up and record odometer: Fill your tank completely and note the odometer reading.
  2. 2Drive normally: Drive until you need fuel again.
  3. 3Fill up and calculate: Fill up again, note gallons added, and divide miles driven by gallons.

Following these 3 steps gives you the final gas mileage (mpg) value.

Skip the Math

If you drove 350 miles and used 14 gallons, your MPG is 350/14 = 25 MPG, which you can compare against EPA ratings.

Use the Free Calculator

Why You Need This Calculation

  • Tracking MPG helps monitor vehicle health, compare cars, and optimize driving habits for fuel savings.

Common Mistakes

Not filling the tank completely both times.

Partial fills give inaccurate gallon measurements.

Resetting the trip meter at the wrong time.

Reset the trip odometer immediately after your first fill-up.

Calculating from a single tank only.

Average multiple tanks for a more accurate MPG figure.

Frequently Asked Questions