MPG to L/100km Converter

Convert miles per gallon to litres per 100 kilometres.

Fuel Economy (MPG)

Gallon Type

L/100km

7.84 L/100km

km/L

12.75 km/L

Quick Reference (US MPG)

Description	US MPG	L/100km	km/L
City driving (poor)	20	11.76	8.50
Average car	30	7.84	12.75
Fuel-efficient sedan	40	5.88	17.01
Hybrid	50	4.70	21.26
Economy car	60	3.92	25.51

MPG vs L/100km

MPG (miles per gallon) is used in the US and UK. L/100km (litres per 100 kilometres) is used in most of Europe, Australia, and Asia. Higher MPG = better; lower L/100km = better. Formula: L/100km = (gallons_in_litres × 100) / (MPG × 1.609344). Note: the US and UK gallon differ — 1 US gal ≈ 3.785 L, 1 UK (imperial) gal ≈ 4.546 L.

Built and maintained by Meet Shah · Last updated 19 July 2026

What this tool is used for

Converting a US window-sticker figure into the metric form the rest of the world quotes.
Comparing an imported vehicle's rating against local metric specifications.
Converting a fleet average for a report that uses metric units.
Understanding what an MPG figure means in litres for a given journey.
Comparing an older imperial figure against a modern metric one.

Frequently Asked Questions

What is the formula?: L/100km = 235.215 ÷ mpg for US gallons, or 282.481 ÷ mpg for imperial. Because it is a division rather than a multiplication, the conversion is its own inverse — the same constant works in both directions.
Why do the same cars show different mpg in the US and UK?: Because an imperial gallon is 4.546 litres against the US gallon's 3.785 — about 20% larger. The same car genuinely returns a higher NUMBER in UK mpg without being any more efficient.
Do official figures match real driving?: Rarely. WLTP (Europe) and EPA (US) test cycles are standardised for comparability, not realism, and real-world consumption typically runs 10-25% worse. The older NEDC cycle was worse still, which is why WLTP replaced it.
How do I compare an electric car?: Not through either unit — use kWh/100km or MPGe, which converts electricity to a gasoline-equivalent energy. MPGe is useful for cross-comparison but says nothing about running cost, since energy prices differ per unit.
Why does efficiency drop at motorway speed?: Because aerodynamic drag rises with the SQUARE of speed, so it dominates above roughly 80 km/h. That is why a car's best economy usually sits well below its top cruising speed, and why small speed reductions save disproportionate fuel.
Why does the conversion invert the comparison?: Because one measures distance per fuel and the other fuel per distance, so higher is better in mpg and worse in L/100km. A car improving from 30 to 40 mpg goes from 7.84 to 5.88 L/100km — the numbers move in opposite directions.

Common errors and gotchas

Assuming the conversion is a simple factor. The quantities are reciprocal, so it is a division rather than a multiplication.
Using the wrong gallon. A UK gallon is about 20% larger than a US one, and both are quoted as MPG.
Reversing the sense of better and worse between the two units.
Averaging before converting, which for a reciprocal quantity gives a different answer from converting then averaging.
Ignoring that the two markets measure consumption on different test cycles.