Enter a fuel-economy figure in one unit and instantly see it expressed in MPG (US), MPG (UK), litres per 100 km and kilometres per litre.
| Unit | Value | Better when |
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The highlighted row is the unit you entered. L / 100 km is an inverse measure: it counts fuel used per fixed distance, so a lower number is better. MPG and km / L count distance per fixed fuel, so a higher number is better.
Each block is one real-world economy level. The green bars (MPG and km / L) grow as the car gets more efficient; the red L / 100 km bar shrinks. Reading the same level across all four units shows how the scales line up.
For beginners: how to read this result
Type your fuel-economy figure into the single value field, then pick which unit it is in using the unit selector. The calculator immediately restates that one figure in all four common units at once and highlights the row matching the unit you entered, so you can read the conversion both ways.
The four units and what they measure
Fuel economy is reported in two different styles, and they run in opposite directions.
- MPG (US) – miles travelled per US gallon of fuel. A higher number is better.
- MPG (UK) – miles travelled per imperial (UK) gallon. A UK gallon is larger than a US gallon, so the same vehicle shows a higher MPG figure on the UK scale. A higher number is better.
- Litres per 100 km – litres of fuel used to cover a fixed 100 km. This is an inverse measure: a lower number means a more efficient vehicle.
- Kilometres per litre – distance covered on one litre of fuel. A higher number is better.
How the conversion works
Every figure is first converted into one common base, litres per 100 km, and the other three units are then derived from that base. The conversion uses fixed, exact constants: one US gallon is 3.785411784 litres, one UK gallon is 4.54609 litres, and one mile is 1.609344 kilometres. From these, miles per US gallon divided into 235.214583 gives litres per 100 km; miles per UK gallon divided into 282.480936 gives litres per 100 km; and 100 divided by kilometres per litre also gives litres per 100 km. Converting through a single base keeps all four results consistent with one another.
Why direction matters
Because litres per 100 km is an inverse measure, it does not move in step with MPG and kilometres per litre. As a car becomes more efficient its MPG and km per litre figures rise while its litres per 100 km figure falls. The all-units table marks each unit as better when higher or better when lower so the direction is never ambiguous, and the quick-reference ladder shows a range of common economy levels side by side in every unit.
What is not included
This tool performs an exact unit conversion only. It does not estimate fuel cost, trip distance or tank range, and it does not predict real-world consumption, which varies with driving style, load, terrain, weather and traffic. Official manufacturer or test-cycle figures can differ from what a vehicle achieves in everyday use, so treat any converted value as the same economy expressed differently, not as a guaranteed real result.
