Fuel Economy Converter
Convert between any two km/L units in your browser — instant, accurate, and private.
Example
1 mpg = 1.20095 mpg (UK). Switch the unit menus to convert between any pair.
How it works
Every value is converted through a single km/L base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Fuel economy gets measured differently depending on where a car was sold, which makes converting between these four units a daily reality for anyone importing a vehicle, planning a road trip abroad, or comparing spec sheets. The United States and the United Kingdom both quote miles per gallon, but they use different gallons — the US gallon is 3.785 liters while the imperial (UK) gallon is 4.546 liters — so a UK MPG figure is always about 20% higher than the US figure for the exact same car. Most of Europe and the rest of the metric world instead reports liters per 100 km, or sometimes kilometers per liter.
The key thing to grasp is direction. MPG, MPG (UK), and km/L are all "higher is better" — more distance per unit of fuel. L/100 km is inverted: it measures fuel consumed per fixed distance, so lower is better. Because of that inversion, you cannot convert MPG to L/100 km by simple multiplication; the relationship is reciprocal, which trips up a lot of people doing quick mental math.
Handy rules of thumb worth memorizing:
- To turn US MPG into UK MPG, multiply by roughly 1.2 (e.g., 30 US MPG is about 36 UK MPG).
- To go between US MPG and L/100 km, divide 235.2 by the number (e.g., 235.2 / 30 ≈ 7.8 L/100 km, and the same formula works in reverse).
- 1 km/L equals about 2.35 US MPG, so a car rated at 15 km/L does roughly 35 US MPG.
The most common mistake is assuming a "gallon" is universal and treating a UK MPG rating as if it were American — that alone makes a car look 20% thirstier or thriftier than it really is. The second trap is averaging fuel economy figures directly: because L/100 km is the only linear measure here, averaging MPG values across a mixed trip overstates real efficiency. When accuracy matters, convert to L/100 km first, average those, then convert back.
Frequently asked questions
What does the fuel economy converter do?
It converts between common km per L units instantly. Pick a unit to convert from and a unit to convert to, type a value, and the result updates live.
Which units does this converter support?
It includes 4 units: MPG (US), MPG (UK), Kilometer/liter, Liter/100 km.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
Why is UK MPG higher than US MPG for the same car?
Because the imperial gallon (4.546 liters) is larger than the US gallon (3.785 liters), the same car travels farther on one UK gallon. UK MPG is roughly 1.2 times the US MPG figure, so 25 US MPG equals about 30 UK MPG.
How do I convert MPG to L/100km?
Divide 235.2 by the US MPG value to get liters per 100 km. For example, 40 MPG becomes 235.2 / 40 = 5.88 L/100 km. The same formula works in reverse because the relationship is reciprocal.
Is a higher or lower number better for fuel economy?
For MPG, MPG (UK), and km/L, higher is better since they measure distance per unit of fuel. For L/100 km it is the opposite — lower is better, because it measures how much fuel is burned over a fixed distance.
What is 100 km/L in MPG?
1 km/L equals about 2.352 US MPG and about 2.825 UK MPG. So a value of 100 km/L is roughly 235 US MPG or 282 UK MPG, figures typically only seen with electric or hybrid efficiency equivalents.
How many km/L is good fuel economy?
Around 15 km/L (about 35 US MPG or 6.7 L/100 km) is solid for a modern petrol car, while efficient hybrids reach 20-25 km/L. Anything below 8 km/L is considered thirsty.
Why can't I just average MPG figures from different trips?
Because MPG is not linear with fuel used, averaging MPG values overstates real efficiency. Convert each leg to L/100 km, average those numbers, then convert back to MPG for an accurate combined figure.
What does L/100km mean and where is it used?
L/100 km means liters of fuel consumed to travel 100 kilometers, and it is the standard in most of Europe, Australia, and Canada. Lower numbers indicate a more efficient vehicle.
How do I convert L/100km to km/L?
Divide 100 by the L/100 km value. For example, 5 L/100 km equals 100 / 5 = 20 km/L, and 8 L/100 km equals 12.5 km/L.
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