Fuel Consumption Converter

Distance-per-fuel units, such as miles per US gallon, miles per imperial gallon, and kilometres per litre, all describe efficiency directly: a bigger number means the vehicle travels farther on the same amount of fuel. Fuel-per-distance units, such as litres per 100 kilometres, litres per kilometre, and gallons per 100 miles, describe the opposite idea: a bigger number means the vehicle burns more fuel to cover the same distance, so a smaller number is now the more efficient one.

Because these two families measure inverse relationships, the converter can't simply multiply by a fixed factor when switching between them. Instead, it first converts the distance-per-fuel value into a common measure, kilometres per litre, then takes the reciprocal of that number when the target unit belongs to the fuel-per-distance family, or vice versa when going the other direction. This reciprocal step means a value of zero has no meaningful conversion in either direction, since travelling zero distance on any amount of fuel, or burning zero fuel over any distance, doesn't correspond to a real efficiency figure.

Choose your source and target units from the from and to menus, enter a number, and the converted figure appears at once, backed by a table listing the value across every supported unit. Adjustable precision controls the number of decimal places shown, and a swap button reverses the conversion direction instantly.

Suppose a car is rated at 30 mpg (US) and you want that figure in litres per 100 kilometres. Using the direct relationship, L/100km = 235.214583 ÷ 30 = 7.84 L/100km. This means the car burns about 7.84 litres of fuel to travel 100 kilometres.

Entering 30 into the mpg (US) field with L/100km selected as the target returns 7.84 L/100km immediately. The accompanying unit table also shows that same rating equals about 12.75 km/L and roughly 36.03 mpg (UK), since imperial and US gallons hold different volumes even though both use the word 'gallon.'