Fuel & units
L/100 km to MPG: exact conversion
L/100 km is common in Europe, Australia and many manufacturer specifications. If you are used to MPG, the number can feel backwards: a higher L/100 km figure means the car uses more fuel. The conversion is an inverse relationship, not a straight multiplication.
Quick answer
MPG UK = 282.480936 ÷ L/100 km. MPG US = 235.214583 ÷ L/100 km. For a quick estimate, 7 L/100 km is about 40.4 MPG UK or 33.6 MPG US.
In this guide
Key takeaways
- Lower L/100 km is better.
- MPG and L/100 km move in opposite directions.
- Choose the UK or US constant based on the gallon you need.
Why the relationship is inverse
MPG measures distance per unit of fuel. L/100 km measures fuel per fixed distance. If a car uses fewer litres to cover 100 km, it can travel further on a gallon, so MPG rises.
That is why you divide by L/100 km instead of multiplying. Doubling L/100 km halves the MPG figure, roughly speaking, before the constants are applied.
MPG (UK) = 282.480936 ÷ L/100 km MPG (US) = 235.214583 ÷ L/100 km km/L = 100 ÷ L/100 km
A few useful examples
These values are rounded. Use the calculator when you need a precise answer for a comparison or a cost estimate.
| L/100 km | MPG UK | MPG US | km/L |
|---|---|---|---|
| 5.0 | 56.5 | 47.0 | 20.0 |
| 7.0 | 40.4 | 33.6 | 14.3 |
| 9.0 | 31.4 | 26.1 | 11.1 |
| 12.0 | 23.5 | 19.6 | 8.3 |
When to use each unit
Use L/100 km when you want to compare fuel consumption directly. A drop from 8 to 7 L/100 km is a clear improvement, and the difference is easy to see. Use MPG when that is the convention your audience expects, but label it as UK or US.
For cost work, L/100 km is often the simplest starting point in metric countries: litres used = kilometres × L/100 km ÷ 100. Then multiply by the price per litre.
Questions
Is lower L/100 km better?
What is 7 L/100 km in MPG?
How do I convert L/100 km to km/L?
Sources
- NIST — unit conversion — US customary and metric relationships used by the converters.
- UK Weights and Measures Act 1985 — Statutory context for UK units, including the imperial gallon.
- fueleconomy.gov — US fuel-economy ratings — EPA label values, test-cycle context and consumer guidance.
- GOV.UK — weekly road fuel prices — UK price statistics for context, not a live station price.
- US EIA — gasoline and diesel prices — US regional and national averages.
Try the calculator
Related guides
MPG to L/100 km: exact conversion
Convert MPG to L/100 km with the right constant for UK and US gallons, including worked examples and common mistakes.
km/L to MPG: Japan, India and Korea
Understand kilometres per litre, convert it to MPG UK or US, and see why km/L is the inverse of L/100 km.
Fuel economy vs consumption
MPG and km/L measure distance per fuel. L/100 km measures fuel per distance. Here is why the distinction matters for comparisons and costs.
A note on prices and rules
Page last reviewed: . Formulas are covered by automated tests. Prices are inputs, not live data.