# How to Calculate the Fuel Mileage of a Semi Truck

by Chrissie ReinhartKnowing how many miles you can drive on a tank of fuel helps you estimate how often you'll need to fill up and gives you a starting place for working to improve your mileage. Figuring out your fuel mileage isn't tricky, but it does take some extra steps that you might not be used to. Taking those steps is worth it so you can accurately figure out how many miles you get per gallon.

#### Step 1

Fill up your tank. Get a receipt and write the current mileage on the receipt. Put the receipt somewhere you'll be able to find it again.

#### Step 2

Find the first receipt the next time you fill up. Get another receipt for the new transaction and write down the new mileage on that receipt.

#### Step 3

Figure out how many miles you traveled by subtracting the mileage on the first receipt from the mileage on the second receipt. For example, If the mileage on your first receipt is 14,100 and the mileage on your second receipt is 14,880, you've driven 780 miles.

Divide the number of miles you've driven (780 in this example) by the number of gallons of fuel used. This will be the number of gallons you bought on the second receipt. For example: you started with a full tank, and to refill the tank, you bought 120 gallons of fuel. You would divide 780 by 120 gallons. You get 6.5 miles to a gallon.

#### Tip

- The number of miles per gallon is rounded to the nearest hundredth. If the third number after the decimal is 5 or higher, round the second number after the decimal up (5.888 is rounded to 5.89). If the third number after the decimal is 4 or lower, keep the second number after the decimal the same (5.883 is rounded to 5.88).

- Semi image by Andrew Breeden from Fotolia.com