Fuel Consumption Calculator

What Is a Fuel Consumption Calculator?

A fuel consumption calculator determines how efficiently a vehicle uses fuel over a given distance. It can convert between common measurements such as litres per 100 kilometres (L/100 km), miles per gallon (MPG), litres per kilometre and fuel used per mile.

The calculator is useful for comparing vehicles, estimating journey costs, checking real-world fuel economy and understanding how much fuel a vehicle requires for a particular distance. It supports kilometres and miles as well as litres, UK imperial gallons and US gallons.

Why Use a Fuel Consumption Calculator?

Fuel economy may be displayed in different ways depending on the country, vehicle manufacturer or information source. Converting between these measurements manually can be inconvenient and can lead to errors, particularly when comparing UK MPG with US MPG.

How to Use the Fuel Consumption Calculator

Enter the distance travelled and the amount of fuel used. Select the appropriate units, then optionally enter the fuel price to estimate the journey cost.

1. Enter the distance. — Enter the distance covered and choose kilometres or miles.
2. Enter the fuel used. — Enter the amount of fuel consumed and select litres, UK gallons or US gallons.
3. Enter the fuel price. — Optionally enter the price of the fuel and select whether the price is per litre, UK gallon or US gallon.
4. Calculate the results. — Select Calculate to display fuel consumption, UK MPG, US MPG, fuel usage per distance and estimated fuel cost.

Fuel Consumption and MPG Explained

Fuel consumption is commonly expressed as litres per 100 kilometres (L/100 km) in many countries. This measurement represents the number of litres required to travel 100 kilometres. A lower L/100 km value means less fuel is required for the same distance.

Miles per gallon (MPG) expresses fuel economy differently. It measures how many miles can be travelled using one gallon of fuel, so a higher MPG value generally indicates better fuel economy. The UK imperial gallon contains approximately 4.54609 litres, while the US gallon contains approximately 3.78541 litres. Consequently, UK MPG and US MPG values are not interchangeable.

Litres per 100 Kilometres

L/100 km is a consumption measurement rather than an economy measurement. For example, a vehicle using 6 L/100 km requires six litres of fuel to travel 100 kilometres under the conditions represented by that measurement. The lower the number, the less fuel the vehicle uses over a fixed distance.

UK MPG and US MPG

UK MPG uses the larger imperial gallon, while US MPG uses the smaller US gallon. A vehicle therefore produces a numerically higher MPG figure when expressed using UK gallons than when expressed using US gallons, even though the underlying fuel consumption is identical.

How Fuel Consumption Is Calculated

Once the entered values have been converted into consistent units, fuel consumption in litres per 100 kilometres is calculated by dividing litres of fuel used by kilometres travelled and multiplying the result by 100.

For MPG calculations, the distance and fuel quantity are converted to the appropriate miles and gallon units before dividing distance by fuel used. Fuel cost is calculated by converting the entered fuel quantity and price to a common fuel unit and multiplying the amount of fuel by the corresponding price.

Understanding Your Fuel Economy Results

Fuel consumption figures should be compared using the same measurement system. When comparing L/100 km figures, a lower value indicates better fuel economy. When comparing MPG figures, a higher value indicates better fuel economy.

Real-world fuel consumption may differ from official vehicle figures. Acceleration, speed, traffic, tyre pressure, road conditions, temperature, weather, vehicle weight, driving style and the use of heating or air conditioning can all affect fuel consumption.

Frequently Asked Questions