Calculating your mileage cost is a reliable way to determine the amount of money you need to reach a destination. By calculating your vehicle's miles per gallon, or MPG, you can determine the amount of miles you can drive on one gallon of gas. Using this number, the amount of miles to your destination and the current price of gasoline, you can easily determine the amount it costs for gasoline to reach your destination.

Fill your vehicle's gas tank completely with gasoline and reset the trip odometer to zero. If your vehicle does not have a trip odometer, write down your vehicle's current mileage.

Drive your car until you need to refuel.

Refuel your vehicle's gas tank completely with gasoline and write down the amount of gallons you pumped and the price per gallon.

Write down the amount of miles driven between fuelling. If your car has a trip odometer, write down the amount of miles displayed. If it does not, subtract the current mileage from the mileage documented when you initially fuelled your vehicle.

Divide the amount of miles driven by the amount of gallons you pumped. For example, if you drove 315 miles and used 16.21 gallons of gas, you divide 315 by 16.21. Your result is 19.43 MPG. If the current gas price is £1.80 per gallon, you can drive 19.43 miles for £1.80.

Divide the number of miles to your destination by your MPG. If your destination is 450 miles, divide 450 by 19.43. Your result is 23.16. This is how many gallons of gas it will take for you to reach your destination.

Multiply the amount of miles by the price per gallon. For instance, the price per gallon is £1.80 and you need 23.16 gallons of gas, multiply £1.80 by 23.16. Your result is 66.0. It will cost £42.9 in gasoline to drive 450 miles.

#### Tip

Your mileage will vary according to how and where you drive, driving conditions and fuel variations.