MPG Calculator

What Is an MPG Calculator?

An MPG calculator determines a vehicle's fuel economy by comparing the distance travelled with the amount of fuel consumed. MPG stands for miles per gallon and is commonly used to describe how efficiently a car, van or other vehicle uses fuel.

This calculator converts your measurements into UK MPG and US MPG while also providing litres per 100 kilometres and kilometres per litre. This makes it useful when comparing fuel economy figures reported using different measurement systems.

Why Use MPG Calculator?

The calculator handles the required unit conversions automatically, allowing you to calculate fuel economy without manually converting kilometres, miles, litres or gallons.

How to Use MPG Calculator

Use the calculator with measurements from a journey, fuel log or vehicle fuel economy test.

1. Enter the distance travelled — Enter the total distance and select kilometres or miles.
2. Enter the fuel used — Enter the amount of fuel consumed and select litres, UK gallons or US gallons.
3. Calculate the MPG — Select the Calculate MPG button to process the measurements.
4. Review the results — The calculator displays UK MPG, US MPG, litres per 100 km, kilometres per litre and additional converted measurements.

How to Calculate Miles Per Gallon

MPG is calculated by dividing the distance travelled in miles by the amount of fuel consumed in gallons. The calculation is straightforward, but the type of gallon must be taken into account. A UK imperial gallon is approximately 4.54609 litres, while a US gallon is approximately 3.78541 litres.

For example, if a vehicle travels 100 miles and uses 10 UK gallons of fuel, its fuel economy is 10 UK MPG. If the same measurements are expressed using US gallons, the resulting US MPG will be different because a US gallon contains less fuel than an imperial gallon.

UK MPG vs US MPG

UK MPG and US MPG are different measurements. UK MPG uses imperial gallons, while US MPG uses US gallons. Because an imperial gallon is larger, a vehicle's UK MPG figure is numerically higher than its US MPG figure for the same underlying fuel consumption.

MPG and Litres per 100 Kilometres

Litres per 100 kilometres, commonly written as L/100 km, measures the amount of fuel required to travel 100 kilometres. Unlike MPG, a lower L/100 km figure represents better fuel economy because less fuel is required to cover the same distance.

Understanding Your MPG Results

A higher MPG figure generally means a vehicle can travel further on the same amount of fuel. However, MPG should be compared using the same measurement standard. UK MPG and US MPG should not be compared directly without converting between the two systems.

Actual fuel economy can differ from calculated or manufacturer figures. Acceleration, cruising speed, traffic, road gradients, temperature, wind, tyre pressure, vehicle weight, air conditioning and driving conditions can all affect fuel consumption. For a representative result, use accurate distance and fuel measurements collected over a suitable journey or several journeys.

Frequently Asked Questions