How to Convert Miles Per Gallon to Km Per Litre

Convert miles into kilometers. Since a kilometer is shorter than a mile, and there are 1.61 kilometers in every mile, you will have to multiply to get the answer. Doing the math (25 x 1.61 = 40.25) shows that 25 miles is equivalent to 40.25 kilometers.

Convert gallons into litres. Since a litre is smaller than a gallon, you must again multiply to get the answer. There are 3.79 litres in every gallon. Here the math is simple, because you are using only 1 gallon. 1 x 3.79 = 3.79, so a gallon of gas is equal to 3.79 litres.

Perform the calculation to determine how many kilometers are attributable to each litre of fuel consumed. Since you have determined that the vehicle traveled 40.25 kilometers on 3.79 litres of fuel, simple division will tell you how many kilometers are traveled on 1 litre. 40.25 ÷ 3.79 = 10.62. 25 mpg is therefore equivalent to 10.62 km/l.

Create a conversion factor, based on the above calculations. One mile is equal to 1.61 kilometers. One gallon is equal to 3.79 litres. Simple division will give you a conversion factor. 1.61 ÷ 3.79 = 0.425. This means that 0.425 km/l equals 1 mpg. You can use the newly calculated conversion factor by multiplying miles per gallon by 0.425. Checking your previous work, 25 mpg x 0.425 = 10.62 km/l, which is identical to the answer in the three-step calculation above.