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Fuel Economy Calc

Convert fuel economy between MPG (US/UK), L/100km and km/L for free. Enter one value and see all units instantly, with a fuel-cost estimate per 100 km.

Fuel consumption

Enter a value in any unit to convert to all others.

Results

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How the conversions work

All units describe the same thing, distance per fuel or fuel per distance, so the tool converts your input to L/100 km first and then derives every other unit from it with exact constants.

US and UK gallons differ (3.785 vs 4.546 liters), which is why MPG figures differ between the two. The tool keeps both so imported car specs compare correctly.

Reading your result

Lower L/100 km means better economy; higher MPG or km/L means better economy. The optional price field turns consumption into money: cost per 100 km at your local pump price.

Real-world driving usually beats lab figures by 10 to 20 percent, so treat manufacturer numbers as a best case.

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Fuel Economy Calc FAQs

What is a good L/100 km figure?
Roughly: under 6 is efficient, 6 to 9 is average for petrol cars, above 10 is thirsty. Hybrids often sit at 4 to 5.
Why do US and UK MPG differ?
The imperial gallon is about 20 percent larger than the US gallon, so the same car shows a higher MPG number in the UK. Always check which gallon a figure uses.
Is L/100 km or km/L better?
They are reciprocals of the same measurement. L/100 km is standard in most of the world and makes cost math easy; km/L reads more intuitively as distance per liter.
How accurate is the cost estimate?
It multiplies your consumption by the price you enter, so it is exact for that price. Real costs vary with driving style, traffic and fuel price changes.
Does it handle electric cars?
Not directly. EVs use kWh/100 km, a different unit. Divide your electricity price per kWh by the same logic manually for now.
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