Fuel Economy Converter
Convert fuel economy between kilometers per liter, liters per 100 kilometers, US MPG, and UK Imperial MPG with all equivalent values shown together.
Last updated: July 2026
US MPG and UK MPG use different gallons
US MPG and UK MPG are not the same because the US gallon and Imperial gallon have different volumes. One US gallon is 3.785411784 liters; one Imperial gallon is 4.54609 liters. For the same fuel consumption, UK MPG is numerically higher than US MPG.
Converted fuel economy
How to read the result
Higher is better
km/L, US MPG, and UK MPG
Lower is better
L/100 km
Formula used
Every result is derived directly from the unrounded km/L base value rather than from a rounded displayed value.
What this fuel economy converter tells you
Enter one positive fuel-economy value to see the equivalent kilometers per liter, liters per 100 kilometers, US miles per gallon, and UK Imperial miles per gallon. The conversion is mathematical only; it does not calculate trip cost, emissions, manufacturer ratings, or real-world vehicle consumption.
How km/L and L/100 km are related
These units are reciprocals. Liters per 100 kilometers equal 100 divided by kilometers per liter, and kilometers per liter equal 100 divided by liters per 100 kilometers. Because L/100 km measures fuel used over a fixed distance, a lower value represents better fuel economy.
How to convert km/L to US MPG
Multiply km/L by 3.785411784 liters per US gallon, then divide by 1.609344 kilometers per mile. For example, 10 km/L equals approximately 23.52145833 US MPG.
How to convert MPG to L/100 km
First convert the selected US or Imperial MPG value to the unrounded km/L base value. Then divide 100 by that base. This direct approach avoids chaining rounded display values and keeps all results internally consistent.
US MPG versus UK MPG
A US gallon is exactly 3.785411784 liters, while an Imperial gallon is 4.54609 liters. The larger Imperial gallon produces a numerically higher UK MPG value for the same underlying fuel economy. Neither unit is inherently more accurate; they describe consumption using different gallon definitions.
Why lower L/100 km means better fuel economy
L/100 km reports how much fuel is consumed to travel 100 kilometers, so using fewer liters is better. km/L and MPG instead report distance traveled per unit of fuel, so higher values are better. The calculator does not apply arbitrary labels such as efficient or inefficient.
Worked examples
10 km/L
10 km/L equals 10 L/100 km, approximately 23.52145833 US MPG, and approximately 28.24809363 UK MPG. At two decimal places, the displayed values are 10 km/L, 10 L/100 km, 23.52 US MPG, and 28.25 UK MPG.
8 L/100 km
Eight liters per 100 kilometers equals 12.5 km/L, approximately 29.40182292 US MPG, and approximately 35.31011704 UK MPG.
30 US MPG
Using 30 × 1.609344 ÷ 3.785411784 gives approximately 12.75431122 km/L. That equals approximately 7.84048611 L/100 km and 36.02849777 UK MPG.
40 UK MPG
Using 40 × 1.609344 ÷ 4.54609 gives approximately 14.1602476 km/L. That equals approximately 7.06202341 L/100 km and 33.30696739 US MPG.
Frequently asked questions
How many MPG is 10 km/L?
It is approximately 23.52 US MPG or 28.25 UK MPG. Specify the gallon system when comparing MPG.
How do I convert MPG to L/100 km?
Convert MPG to km/L using the appropriate US or Imperial gallon, then divide 100 by the unrounded km/L value.
Why is L/100 km reversed compared with MPG?
L/100 km measures fuel used for a fixed distance; MPG measures distance traveled with a fixed fuel volume.
Is higher MPG better?
Yes. Higher MPG means more miles traveled per gallon, provided the same US or Imperial gallon definition is used.
Is lower L/100 km better?
Yes. A lower value means fewer liters are used to travel 100 kilometers.
What is the difference between US MPG and Imperial MPG?
They use different gallon volumes: 3.785411784 liters for a US gallon and 4.54609 liters for an Imperial gallon.
Why is UK MPG higher for the same fuel economy?
The Imperial gallon is larger, so the same vehicle can travel more miles per Imperial gallon than per US gallon.
Can I use this for diesel and gasoline vehicles?
Yes. Fuel type does not change the mathematical unit conversion.
Does this calculate actual fuel consumption?
No. It converts an entered rating or measurement without predicting real-world performance.
Does it account for traffic, weather, or driving style?
No. Actual consumption varies with speed, traffic, weather, load, tires, terrain, maintenance, and driving style.
Can I use manufacturer fuel-economy ratings?
Yes, for unit conversion. Manufacturer ratings come from specific test cycles and are not guaranteed real-world results.