TravelMath provides an online driving cost calculator to help you determine how much you'll spend on gas for your next road trip. You can enter airports, cities, states, countries, or zip codes to compute the cost of driving between locations. Driving distances are calculated using actual driving directions if they are available, or a GPS-accurate method for the straight line distance. Automatic estimates are provided for local gas prices and vehicle fuel efficiency in miles per gallon (mpg) or liters per 100 kilometers (L/100 km), based on the make and model of your car, SUV, or minivan. Don't let the economy and rising oil prices stop you from taking your next trip. You can use this tool to find out if it's cheaper to fly or drive to your destination.