Kilometers per Liter to MPG Converter (US & UK)
Convert fuel economy between kilometers per liter (km/L), US miles per gallon (mpg US), and UK miles per gallon (mpg UK). Bidirectional, instant, and precise.
Fuel Economy Converter
Type a value in km/L to see the equivalent mpg (US & UK).
Or start from US mpg and convert to km/L and UK mpg.
Imperial gallon used in the UK, Canada, and some other countries.
Common fuel economy presets
Enter a value in any field to see the equivalent fuel economy in the other units.
How to convert km per liter to miles per gallon
Fuel economy can be expressed either as kilometers per liter (km/L) or miles per gallon (mpg). Because the mile and the gallon are different in the US and UK, there are two mpg values:
- mpg (US) – uses the US gallon (3.785 L)
- mpg (UK) – uses the imperial gallon (4.546 L)
Conversion formulas
From km/L to US mpg:
\(\text{mpg}_{US} = \text{km/L} \times 2.35214583\)
From km/L to UK mpg:
\(\text{mpg}_{UK} = \text{km/L} \times 2.82480936\)
From US mpg to km/L:
\(\text{km/L} = \text{mpg}_{US} \times 0.42514371\)
From UK mpg to km/L:
\(\text{km/L} = \text{mpg}_{UK} \times 0.35400619\)
Example: 15 km/L to mpg
Suppose your car averages 15 km/L and you want to know the equivalent mpg:
- US mpg: \(15 \times 2.35214583 \approx 35.28\) mpg (US)
- UK mpg: \(15 \times 2.82480936 \approx 42.37\) mpg (UK)
So 15 km/L corresponds to about 35.3 mpg (US) or 42.4 mpg (UK).
Quick reference table: km/L to mpg
The table below shows common fuel economy values converted between km/L, US mpg, and UK mpg.
| km/L | mpg (US) | mpg (UK) |
|---|---|---|
| 8 | 18.82 | 22.60 |
| 10 | 23.52 | 28.25 |
| 12 | 28.23 | 33.90 |
| 15 | 35.28 | 42.37 |
| 18 | 42.34 | 50.85 |
| 20 | 47.04 | 56.50 |
US mpg vs UK mpg: why are they different?
The difference comes from the size of the gallon:
- 1 US gallon = 3.78541 liters
- 1 UK (imperial) gallon = 4.54609 liters
Because the imperial gallon is larger, the same car will always show a higher mpg value in UK mpg than in US mpg, even though its real fuel consumption is identical.
What is a “good” fuel economy?
Very roughly, for passenger cars:
- 10 km/L ≈ 23.5 mpg (US) – average for older or larger vehicles
- 15 km/L ≈ 35.3 mpg (US) – decent for many compact cars
- 20 km/L ≈ 47.0 mpg (US) – efficient small cars and some hybrids
Real-world fuel economy depends on driving style, traffic, terrain, temperature, and tire pressure. Use this converter to compare your own numbers with manufacturer ratings or with cars sold in other countries.
FAQ: km/L to mpg
How do you convert km per liter to miles per gallon (US)?
Multiply the value in km/L by 2.35214583:
Example: \(15 \text{ km/L} \times 2.35214583 \approx 35.28 \text{ mpg (US)}\).
How do you convert km per liter to miles per gallon (UK)?
Multiply the value in km/L by 2.82480936:
Example: \(15 \text{ km/L} \times 2.82480936 \approx 42.37 \text{ mpg (UK)}\).
Can I convert mpg back to km/L?
Yes. Use the inverse factors:
- \(\text{km/L} = \text{mpg}_{US} \times 0.42514371\)
- \(\text{km/L} = \text{mpg}_{UK} \times 0.35400619\)
The calculator on this page is fully bidirectional: you can start from km/L, US mpg, or UK mpg and the other fields will update automatically.
Which unit should I use?
- km/L – common in many metric countries (e.g., parts of Asia and South America).
- mpg (US) – used in the United States.
- mpg (UK) – used historically in the UK and still common in some English-speaking countries.
When comparing cars across regions, always make sure you are comparing the same mpg standard (US vs UK) or convert everything to km/L.