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How much gas will you use on your road trip?

Calculating the Cost of Gas for a Road Trip

Fuel costs for long road trips can be startlingly high, especially if you don't know what to expect ahead of time. Luckily, calculating the cost of gas for your road trip is a matter of simple arithmetic, and there are even several Web sites that will do the math for you.

Before you can determine the cost of gas for your road trip, you need to figure out your vehicle's gas mileage. Typically, this number is listed in your owner's manual or can be found on the Internet. If not, you can calculate it yourself by first filling up the tank and resetting the trip odometer. Once you've used at least half of the gasoline in the tank, fill the tank again and note how much fuel you put in the car, as well as the mileage on the odometer. Then divide the number of miles by the gallons of fuel to get your vehicle's miles per gallon (MPG) rating. For example, if you traveled 250 miles on 10 gallons of gasoline, your car's MPG rating is 25.

Once you know your car's MPG, you can calculate the amount of fuel you'll need on your road trip. First, find out how many miles you plan to drive by entering your starting and ending points into an online maps program like MapQuest or Google Maps. Then divide this mileage figure by your car's MPG rating to find out how many gallons of fuel you'll need on your trip. For instance, if you plan to drive 500 miles in a car that gets 25 MPG, you'll need about 20 gallons of gasoline. To find out your total fuel cost, visit the American Automobile Association's (AAA) Daily Fuel Gauge Report to determine the average gas prices in the area you'll be driving. Multiply the number of gallons you need times the average gas price to get your total fuel cost. For example, if gas is about $3.50 a gallon in your area and you need 20 gallons to drive your trip distance, you'll pay $75 for gasoline.

Several online calculators make this figuring even easier. Typical of these Web sites is AAA's Fuel Cost Calculator, which allows you to select your departure and arrival cities, as well as the make and model of your car. It then uses the current average price of gasoline in the areas in which you plan to drive to calculate your total fuel cost. offers a similar service, but its calculator can actually schedule your fuel stops based on the lowest gas prices along your route. With these tools, you'll never be surprised when it comes time to fuel up.

For links to fuel cost calculators and other great information, click over to the next page.

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