Before a road trip, it helps to know what the gas will cost. With your distance, your vehicle's fuel economy, and the price at the pump, the math is quick.
The calculation
Divide the trip distance by your miles-per-gallon to get the gallons you'll burn, then multiply by the price per gallon. The cost-per-mile figure is handy for comparing vehicles or estimating longer trips. A more fuel-efficient vehicle lowers both numbers directly.