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Fuel Economy Converter

Convert MPG, liters per 100 km and km per liter.

Result 7.840486119 L/100 km

30 mpg (US) = 7.840486119 L/100 km

All conversions

Miles per gallon (US)30 mpg (US)
Miles per gallon (UK)36.02849782 mpg (UK)
Liters per 100 km7.840486119 L/100 km
Kilometers per liter12.75431121 km/L
Miles per liter7.925161563 mi/L

When to use it

Use this converter to compare fuel economy figures from different countries. Car reviews in the US use miles per US gallon, the UK uses miles per imperial gallon, and most other countries use liters per 100 km or km per liter. Converting them lets you compare cars fairly, plan trip costs and understand rental car figures abroad.

How to use it

  1. Enter the figure in Value.
  2. Choose the unit you have, such as Miles per gallon (US).
  3. Choose the unit you want, such as Liters per 100 km (L/100 km).
  4. Read the result, or click Copy result.
  5. Use the swap button to convert the other way.

The All conversions table shows the same economy in mpg (US), mpg (UK), L/100 km, km/L and miles per liter.

Worked example

An American review says a car gets 30 mpg. Enter 30, choose mpg (US) and L/100 km, and the result is 7.840486119 L/100 km. The table shows 36.03 mpg (UK), so in a British review the same car would look more efficient.

Now compare it with a European car rated at 6 L/100 km. Swap the units and enter 6. That is about 39.2 mpg (US), so the European car uses nearly a quarter less fuel.

Estimating trip fuel

With a figure in L/100 km, multiply by the distance and divide by 100. A 500 km trip at 7.84 L/100 km needs about 39 liters. At 6 L/100 km it needs 30 liters. Multiply the liters by the local fuel price to estimate the cost, and compare the two cars in money rather than in mpg.

Tips

  • Compare in L/100 km. Because it measures fuel used, differences between cars are easier to judge in money terms.
  • Treat official figures as a best case. Real-world economy is often 10 to 20% worse, especially in cities and cold weather.
  • Check which gallon a source uses. Older or international sites may not say.

Common mistakes

  • Assuming bigger is always better. For mpg and km/L it is, but for L/100 km smaller is better.
  • Mixing US and UK mpg. A 20% difference can make a car look better or worse than it is.
  • Averaging mpg figures. To average economy over several trips, add up all the distance and all the fuel, then divide.

Frequently asked questions

Why does a lower L/100 km number mean better economy?

Liters per 100 km measures how much fuel you use, so lower is better. Miles per gallon and km per liter measure how far you go on a set amount of fuel, so higher is better. That is why the conversion is not a simple multiplication.

Why are US and UK mpg different?

A UK (imperial) gallon is about 20% larger than a US gallon. The same car does more miles per UK gallon, so a figure of 30 mpg (US) is about 36 mpg (UK).

How do I work out my car's real fuel economy?

Fill the tank and reset the trip meter. At the next fill-up, note the distance driven and the fuel added. Divide distance by fuel for mpg or km/L, or divide fuel by distance and multiply by 100 for L/100 km.

Can I convert electric car efficiency here?

No. Electric cars are measured in kWh per 100 km or miles per kWh, which describe energy rather than fuel volume. This converter covers liquid fuels only.

Why does the tool reject zero?

A fuel economy of zero has no meaning, and converting it between distance-per-fuel and fuel-per-distance would mean dividing by zero. Enter a number greater than zero.

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