I'm importing a car from Japan rated 18 km/L. How does that compare to UK fuel economy figures?

18 km/L × 2.824809 = 50.8 mpg (Imperial). That's excellent efficiency — comparable to a good petrol hybrid in the UK. Most UK mid-size family cars achieve 40–55 mpg (Imperial) on the official combined cycle.

Why is mpg (Imperial) higher than mpg (US) for the same vehicle?

Because the Imperial gallon is larger (4.546 L vs 3.785 L). A car traveling the same distance uses fewer Imperial gallons than US gallons, so the mpg (Imperial) number is always about 20% higher. Never compare mpg (Imperial) to mpg (US) directly — you'll always overestimate the UK car's efficiency. See also: [km/L to mpg (US)](/fuel/kml-to-mpg/).

Is km/L commonly used anywhere, or only Japan?

km/L is the standard in Japan, South Korea, India, parts of Southeast Asia, and Latin America. It's also used informally in many countries alongside L/100km. European and Australian manufacturers usually publish L/100km instead.

I found a used car listed with a fuel economy rating of 40 mpg (Imperial) but I need to compare it to Japanese market ratings in km/L — how do I convert it back?

Divide by 2.824809. For example, 40 mpg (Imperial) ÷ 2.824809 = 14.2 km/L. Alternatively, use our mpg (Imperial) to km/L converter.

Km per Liter to MPG (Imperial) Converter

Enter a value to instantly convert between fuel economy units.

From

Precision4 dp

1 Km per Liter = 2.8248 MPG (Imperial)

Key Formulas

MPG (US) → Liters per 100km

L/100km = mpg × 235.215

Liters per 100km → MPG (US)

mpg = L/100km × 235.215

Km per Liter → MPG (US)

mpg = km/L × 2.35215

MPG (US) → Km per Liter

km/L = mpg × 0.425144

Formula

mpg (Imperial) = km/L × 2.824809

Buying a car imported from Japan or South Korea and comparing it against UK fuel economy figures? Asian manufacturers typically rate efficiency in kilometers per liter (km/L), while the UK and older Commonwealth countries use miles per Imperial gallon. The Imperial gallon is 4.546 liters — 20% larger than the US gallon — so mpg (Imperial) figures are always higher than mpg (US) for the same car. Converting km/L to mpg (Imperial) lets you make an apples-to-apples comparison when shopping for vehicles or checking running costs.

Source: NIST SP 811, Table B.8

Frequently Asked Questions

Real-World Examples

A typical Japanese market compact car rated 15 km/L converts to 42.4 mpg (Imperial) — strong efficiency by UK standards.

15 km/L = 42.37 mpg imp

A mid-size SUV rated 10 km/L delivers 28.2 mpg (Imperial), roughly average for a family SUV in the UK.

10 km/L = 28.25 mpg imp

A Japanese hybrid at 20 km/L achieves 56.5 mpg (Imperial) — comparable to the UK official economy figures for hybrids like the Toyota Yaris.

20 km/L = 56.5 mpg imp

A larger 4WD truck rated 7 km/L equals 19.8 mpg (Imperial), typical for heavier utility vehicles.

7 km/L = 19.77 mpg imp

mpg to l per 100km l per 100km to mpg kml to mpg mpg to kml

Km per Liter to MPG (Imperial) Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

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