How to Calculate Trip Gas Cost
Knowing the gas cost before a road trip helps you budget and decide how to split expenses.
The formula
Gallons needed = trip distance ÷ miles per gallon. Trip cost = gallons needed × price per gallon. Cost per mile = trip cost ÷ distance.
Example
A 450 mile trip in a car that gets 30 mpg needs 450 ÷ 30 = 15 gallons. With gas at $3.40 a gallon, the cost is 15 × $3.40 = $51.00, or about 11.3 cents a mile. For a round trip, double the distance to get $102.
Splitting the cost
Divide the total fuel cost by the number of people. The $51 one-way trip shared by four people is $12.75 each. Many drivers also split tolls and parking.
Find your real mpg
The number on the sticker is an estimate. To find yours, fill the tank, reset the trip meter, drive normally, then fill up again and divide the miles by the gallons you added. Our MPG Calculator does the division for you.
What changes your fuel use
- Higher highway speeds
- Heavy loads and roof racks
- Low tire pressure
- Heavy use of air conditioning
- Hills, stop-and-go traffic and cold weather
Ways to save fuel
Keep tires inflated to the recommended pressure, avoid hard acceleration, use cruise control on highways and remove cargo you do not need. You can check the fuel economy of many models at fueleconomy.gov.
Calculate your trip
Use our Gas Cost Calculator to enter distance, mpg and gas price and see the total instantly.