Tenn. Code Ann. § 67-3-1204: Amount of tax - Formula

The amount of tax payable to the state is determined by dividing the total number of miles traveled in the state during the quarter or annual reporting period, as the case may be, by the average number of miles of motor vehicle travel per gallon of gasoline or diesel fuel, or the per gallon equivalents of alternative fuels, and multiplying the result by the rates of the tax per gallon as imposed in parts 2 and 11 of this chapter.