What the inputs mean
- Distance: how far you will drive one way. Pick round trip to double it.
- Fuel economy: miles per US gallon, or liters per 100 km with the Metric switch. Your trip computer or your own fill-up records are closer to real life than a window sticker; the MPG calculator works it out from a fill-up.
- Fuel price: what you pay per gallon or per liter, in your currency. The result comes out in the same currency.
- People: how many share the cost.
The formula
fuel used = distance ÷ mpg cost = fuel used × price per gallonIn metric:
fuel used (L) = km × L/100 km ÷ 100 cost = liters × price per literWorked example
A 300-mile drive in a car that gets 25 mpg, with fuel at 3.50 per gallon: 300 ÷ 25 = 12 gallons, and 12 × 3.50 = 42.00. That is 0.14 per mile. Make it a round trip and it is 24 gallons and 84.00; split between two people, 42.00 each.
In metric: 500 km at 7.5 L/100 km uses 37.5 liters. At 1.80 per liter the trip costs 67.50, or 0.135 per km.
Getting a closer number
Fuel economy changes with speed, load, a roof box, towing, cold weather and traffic. Highway driving at a steady speed usually beats a mixed figure, and towing or a loaded roof can pull it down a lot. If you are not sure, run the calculator twice with a good and a bad fuel economy figure to see the range. Fuel prices also change along a route, so use a price you expect to pay, not the cheapest one you have seen. Tolls, parking and wear on the car are not included.
Cost per mile as a quick check
Price per gallon divided by mpg gives the fuel cost of one mile. Multiply by any distance to budget in your head: at 0.14 per mile, a 50-mile daily commute costs 7.00 in fuel.
Questions
How do I calculate gas cost for a trip?
Divide the distance by your mpg to get the gallons, then multiply by the price per gallon. 300 miles at 25 mpg is 12 gallons; at 3.50 per gallon that is 42.00.
How much does it cost to drive 1,000 miles?
It depends on the car and the fuel price. At 30 mpg and 3.20 per gallon, 1,000 miles uses 33.3 gallons and costs about 106.67.
How do I split gas money on a road trip?
Work out the total fuel cost for the whole trip, round trip included, and divide by the number of people. A 600-mile round trip at 25 mpg and 3.50 per gallon costs 84.00, or 42.00 each for two people.
What is my cost per mile for fuel?
Divide the price per gallon by your mpg. At 3.50 per gallon and 25 mpg, fuel costs 0.14 per mile.