Going on a Road Trip? Here’s How to Calculate Your Fuel Costs

Spring is around the corner and if you’re planning to go on an epic road trip with your friends or family, then you might want to know how to calculate your fuel costs. Of course, it’s much easier to just get in your car and hit the open road, but calculating your fuel costs for any road trips can lead to more efficient spending along the way, which means that you can enjoy much more experiences on your trip aside from trying to find a gas station.

How to calculate your average miles per gallon

In order to figure out the type of mileage that your car is able to achieve on any trip, the first thing that you’ll want to do is figure out how many gallons of gas your car’s fuel tank holds. The easiest way to find out is to check out your car’s owner’s manual and flip to “fuel tank” or “capacities” sections and then it will tell you.

After you find that out, fill up your gas tank, reset the trip odometer, and go for a drive. During your drive, you’ll most likely have a mix of highway and city driving scenarios, which will give you a good average of what your car is capable of achieving. And when the tank gets to empty, or “E,” divide the miles driven by the amount that the tank holds.

RV at a RaceTrac gas station in Clermont
An RV at a gas station | Jeffrey Greenberg/Universal Images Group via Getty Images

For example, if your car’s tank holds 15 gallons and you drove 350 miles, then divide 350 by 15, which equals 23.33, or roughly 23 mpg. And if you want to calculate the cost per mile, then you can divide the total miles driven by the total cost to fill up your tank. So, if it costs $2.49 per gallon and you put 15 gallons of gas into your tank, then it will cost a total of $37.35 to fill it up.

Then 350 divided by $37.35 equals 9.3, or roughly 9 cents per mile.

A mule deer grazes beside the road leading to Maroon Lake near Aspen, Colorado. The IIHS says deer whistles 'have not proven effective.'
The IIHS says deer whistles ‘have not proven effective’ | Robert Alexander/Archive Photos/Getty Images

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How to calculate how much gas you will use for your trip

Now that you know how many gallons of gas your car holds and how many miles per gallon it can achieve, on average, you can now calculate how much gas you will use on an entire road trip.

For example, if the road trip that you plan on taking is 1,200 miles long, and you know that your car can achieve an average of 23 mpg (as in the previous example), then you just need to divide the length of the trip by the miles per gallon average.

So, 1,200 divided by 23 equals 52 gallons total.

However, keep in mind that your mileage and fuel costs can vary depending on how many side trips or detours you end up taking.

A diesel truck pulling out of a gas station
A truck pulls out of a gas station | David McNew/Getty Images

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How to find the best gas prices along the way

Lastly, if you want to find the best gas prices in any area while you’re on your road trip, then you can download the Gas Buddy app on your smartphone. This app allows you to not only find the best gas prices, but it can even plan your trip for you by showing you which gas stations to use and tell you how much the total trip will cost.