Gas prices are on the rise yet again, which means it’s time to revisit the conversation about how much it’s costing us as individuals to drive. Why not just look at the owner’s manual? Cars typically perform more poorly as they age. Here are a couple ways to calculate your current fuel economy. One of them is sure to be right for you:

Calculating Miles Per Tank (MPT)

1) To calculate how many miles per tank you’re getting, drive until just after your gas light comes on (Don’t run out of gas!) and fill it all the way up. How many gallons of gas does your car hold? If it’s a small car it could be as few as 9. Larger vehicles such as trucks sometimes hold 30. In most cases it will be somewhere around 15 or 16. Jot down the total mileage on your car’s odometer. While you’re at it, write down how much it cost to fill your tank.

2) When your gas light comes on again and you’re almost out of fuel, take note of the mileage again. Simply finding the difference between your last odometer reading and the new one will tell you how many miles you’re getting per tank. This math is super easy and will help you understand how far your monthly gas budget is getting you. It should look like this:

(New Mileage) – (Old Mileage) = *Total Miles Per Tank

*Total Miles Per Tank can also be easily calculated by pushing the trip odometer button near your speedometer and odometer in the dash each time you fill up. It should be right in front of you while you’re driving if you look, and pushing it wil bring it to zero.

Calculating Miles Per Gallon (MPG)

To find out how many miles per gallon you’re getting, you could divide your MPT from above by the total number of gallons in your tank. For a more official understanding of the number of gallons your car holds, check out your owner’s manual, which usually includes an exact figure. If you’re like my mother, you never let your tank dip below half-empty (She’s an optimist, and paranoid.) so if you haven’t calculated your MPT. Try this:

1) To calculate your miles per gallon, start by writing down the exact number of gallons you pump into your tank next time you fill up. You need not start with an empty tank here — moms of the world, rejoice! — but if your gas gauge is closer to E, you might find your MPG is a little more accurate later on. Once again, take note of your car’s mileage or reset your trip odometer.

2) When you fill up again, find the difference in mileage (as described above) and divide by the number of gallons you put in the tank. Again, be sure to use the most exact numbers possible (including decimal points) to get an accurate calculatoin. It should look like this:

(Miles Driven) / (Gallons Consumed) = Miles Per Gallon

Saving Money on Fuel

Once you understand how many miles per tank and miles per gallon you’re getting you’ll better understand what a few cents difference per gallon at the pump means to you. Test your gas mileage with different grades of gasoline — you may find paying for the more expensive stuff actually means a good enough gas mileage to justify going with it all the time.

To find cheaper gas online, use trusted sites like GasBuddy or Mapquest Gas Prices. There are also a whole bunch of smartphone apps out there to help you save money on gas. Just remember to drive safely!

Have a good tip for saving on gas? Share it in the comments and help a reader out!