The measure is usually expressed in two ways:

- As
**the amount of fuel used per unit distance**; for example, litres per 100 kilometres (**l/100 km**). In this case, the lower the value the more efficient a vehicle is; - As
**the distance travelled per unit volume of fuel used**; for example, kilometres per litre (**km/l**) or miles per gallon (**mpg**). In this case, the higher the value the more efficient a vehicle is.

To convert *x* l/100 km to *y* mpg, perform:

- 235.2146 ÷
*x*l/100 km =*y*mpg (US liquid gallon), or - 282.481 ÷
*x*l/100 km =*y*mpg (Imperial gallon)

- 235.2146 ÷
*a*mpg (US liquid gallon) =*b*l/100 km, or - 282.481 ÷
*a*mpg (Imperial gallon) =*b*l/100 km

- 2.352146 *
*m*km/l =*n*mpg (US liquid gallon), or - 2.82481 *
*m*km/l =*n*mpg (Imperial gallon)

- 0.4251437 *
*c*mpg (US liquid gallon) =*d*km/l, or - 0.354006 *
*c*mpg (Imperial gallon) =*d*km/l