How to Calculate How Far I Can Go on a Tank of Gas

by Matt McGewWhen planning a long trip or preparing a household budget, you may want to know how far your vehicle can go on a tank of gas. To calculate this information, you will need to determine the estimated miles per gallon your vehicle can expect to get in the city and on the highway and the capacity of your vehicle's gas tank. By calculating a weighted average based on your driving habits, you can estimate how far you can go on a tank of gas.

Determine the average mpg of your vehicle. The website Fueleconomy.gov provides the Environment Protection Agency's fuel economy ratings for most cars and trucks manufactured after 1984. Select your vehicle's year, make and model to display the average mpg (city and highway). For example, assume your vehicle averages 20 mpg in the city and 25 mpg on the highway.

Determine how many gallons of gas your vehicle will hold. You can find this information in your vehicle owner's manual. Alternatively, you can fill the car with gas when the vehicle's tank is empty. In this case, the gallons of gas you fill up the gas tank with is the total gallons of gas your vehicle will hold.

Determine the approximate percentage of time you will drive on the highway and in the city. For example, assume you will drive 60 percent on the highway and 40 percent in the city.

Multiply the expected mpg in the city by the estimated percent of time you will drive the vehicle in the city. Continuing the same example, 20 x .40 = 8.

Multiply the expected mpg on the highway by the estimated percent of time you will drive the vehicle on the highway. Continuing the same example, 25 x .60 = 15.

Add the sum from Step #4 by the sum from Step #5. Continuing the same example, 8 + 15 = 23. This figure represents the average mpg you should expect from your vehicle.

Multiply the average mpg figure from Step #6 by the gas tank capacity from Step #2. For example, assume your vehicle's gas tank can hold 20 gallons of gas. 23 x 20 = 460 miles. This figure represents the distance you can expect to go in your vehicle on a tank of gas.