How the fuel cost is worked out
A round trip simply doubles the distance. Divide the total by the number of people in the car for each person’s share of the gas money.
What fuel economy does to a 500-mile road trip
At $3.50 per gallon:
| Fuel economy | Gallons | Fuel cost | L/100 km |
|---|---|---|---|
| 20 mpg | 25.0 | $87.50 | 11.8 |
| 25 mpg | 20.0 | $70.00 | 9.4 |
| 30 mpg | 16.7 | $58.33 | 7.8 |
| 35 mpg | 14.3 | $50.00 | 6.7 |
| 40 mpg | 12.5 | $43.75 | 5.9 |
| 50 mpg | 10.0 | $35.00 | 4.7 |
Going from 25 to 35 mpg on the same trip saves about $20. Driving at a steady 55 to 65 mph instead of 75 to 80, keeping tires at the right pressure and taking roof boxes off usually helps more than people expect. One US gallon is 3.785 liters.
How to use the trip fuel cost calculator
- 1Choose miles with US or UK mpg, or kilometers with liters per 100 km, then enter how far you are going and tick round trip if you are coming back.
- 2Enter your car’s fuel economy and the current price of gas or diesel.
- 3Add the number of people sharing the ride to see each share, then copy the result or send the link to your passengers.
Frequently asked questions
How do I calculate the fuel cost of a trip?
Divide the distance by your car’s fuel economy to get the gallons (or liters) you need, then multiply by the price per gallon (or liter). 300 miles in a car that does 30 mpg needs 10 gallons; at $3.50 a gallon that is $35.
Which fuel economy should I enter?
The figure from your car’s trip computer or your own fill-ups is the most realistic. Official ratings are often a bit optimistic. Highway driving at a steady speed usually uses less fuel than the combined rating, while roof boxes, heavy loads and high speeds use more.
What is the difference between US and UK mpg?
A UK (imperial) gallon is 4.546 liters, a US gallon only 3.785 liters. The same car therefore shows about 20 percent more miles per gallon in the UK. Choose the UK setting if your figure comes from a British source.
How do I convert mpg to liters per 100 km?
Divide 235.2 by the US mpg figure, or 282.5 by the UK mpg figure. 30 US mpg is about 7.8 liters per 100 km. The calculator does this for you and shows both.
How should we split the cost between passengers?
The usual way is to share the fuel equally among everyone in the car, driver included. Enter the number of people and the calculator shows each share. Tolls and parking can be added on top by hand.