Commuting to work or school is often more expensive than other alternatives. If you live fairly close to your commuting destination, it may be more costefficient to walk, ride a bike, or take public transportation. Additionally, gas prices are unpredictable, making strict budgeting a bit of a challenge. On the other hand, the convenience and dependability of your own vehicle make commuting by car an appealing option for most workers and students.
Things You'll Need
 Pen and paper
 Calculator
 Your vehicle's mileage
Determine Miles Per Gallon

Start out with a nearly empty tank of gas.

Fill up your gas tank. Record the amount of gallons you put in the tank on a piece of paper. Let's say you used 20 gallons of gas.

Record your car's mileage on a piece of paper. Let's say your mileage is 2,000.

Drive your car until the tank is almost empty again.

Fill your gas tank. Record the mileage and number of gallons once again. Let's say the new mileage is 2400 miles, and the amount of gallons is still 20.

Subtract the first mileage (2000) from the second (2400) to get the number of miles per tank. The result in this case would be 400.

Divide the mileage result by the second number of gallons. In this case, the result would be 20. This is the number of miles your vehicle gets per gallon. Record this number.
Determine Commuting Mileage

Determine how many miles you have to travel to work. You can do this either on a weekly or monthly basis. Let's say you travel 5 miles one way to work.

Multiply this number by 2 to take into account the round trip. Daily mileage, then, would be 10 miles (assuming you only drive to work and back once a day).

Multiply the number of miles you commute by the number of days you work. Again you can do this on a weekly or monthly basis. Let's say you work 5 days a week. The equation would be 5 days multiplied by 10 miles per day, or 50 miles in one week.

Multiply this result by 4 to calculate monthly mileage: 4 times 50 equals 200 miles per month.
Calculate Commuting Cost

Record the number of miles required for commuting (200 in the example) and the figure for your vehicle's mileage per gallon (20 in this case).

Divide the number of miles you travel per month by the number of miles your vehicle gets per gallon. In our case, the equation would be 200 divided by 20, which equals 10. This is the number of gallons you will need to travel to work each month.

Multiply the number of gallons required for commuting by the price of gas per gallon. Let's say gas rates drop to an alltime low, costing only $2.00 per gallon. In this case, you would spend only $20 per month (10 times 2).
Tips & Warnings
 For a quick way to figure your mileage per gallon, you can visit http:///www.fueleconomy.gov to receive an estimate.
 To find the lowest gas prices in your area, visit http://www.fueleconomy.gov/feg/gasprices/states/index.shtml.
 Since gas mileage varies, these numbers are approximate. However, they are sufficient for planning a monthly budget. These numbers also do not take insurance or other auto expenses into account. Visit http://www.commutesolutions.org/calc.htm, which features more comprehensive commute calculator.
References
 Photo Credit Jupiterimages/Comstock/Getty Images