Record the starting fuel level or fill the tank completely
Record the ending fuel level after the trip or usage period
Measure the distance traveled in miles or kilometers
Calculate fuel used by subtracting ending fuel from starting fuel
Use the formula: Fuel consumption = Fuel used ÷ Distance traveled
Express the result as liters per 100 km, miles per gallon, or km per liter
For liters per 100 km, use: (Fuel used in liters ÷ Distance in km) × 100
For miles per gallon, use: Distance in miles ÷ Fuel used in gallons
For km per liter, use: Distance in km ÷ Fuel used in liters