How to calculate fuel cost and spend less on gas

Knowing what a trip really costs helps you budget, split costs fairly and decide between driving, flying or taking the train.

Open the tool: Fuel Cost Calculator

1. The formula

Gallons = miles ÷ mpg. Cost = gallons × price per gallon. Double the miles for a round trip.

2. Measure your real mpg

Fill the tank, reset the trip meter, drive normally, then fill up again. Miles driven ÷ gallons added is your real mpg. Average over two or three tanks.

3. Ways to use less gas

  • Keep tires at the pressure on the door sticker.
  • Drive at 55–65 mph instead of 75; drag rises fast with speed.
  • Accelerate smoothly and coast to red lights.
  • Remove roof racks and extra weight.
  • Compare prices with a gas price app before you fill up.