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Fuel economy converter

Convert L/100 km and mpg without using the wrong gallon.

This tool processes files and text locally in your browser. Your content is not uploaded or stored by this site.

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What this tool does

Fuel economy is inverted through litres per 100 km. US mpg uses the US gallon; imperial mpg uses 4.54609 L. Zero and negative rates are refused.

How to use it

  1. Enter the economy figure.
  2. Pick L/100 km, km/L, or a labelled mpg.
  3. Convert and copy the JSON.

Supported input

  • A positive number and two fuel-economy units

Output

  • JSON with the converted rate plus every other unit in the family

Privacy

This tool processes files and text locally in your browser. Your content is not uploaded or stored by this site.

ConvertPass does not include your input in analytics, URLs, or error reports. Encoding: Decimal numbers / litre per 100 km. Limit: A single economy figure (4.0 KB).

Limitations

  • WLTP, NEDC, and EPA test cycles are not applied. This is arithmetic on a number you already have.
  • Miles per gallon US and imperial differ. The menu says which gallon.
  • Electric kWh/100 km is not in this family.

Example

Input
10 L/100 km → mpg US
Output
{
  "result": 23.5214583305,
  "formatted": "10 L/100km = 23.5214583305 mpg US"
}

Troubleshooting

A UK mpg looks optimistic next to US mpg
The imperial gallon is larger, so imperial mpg is a bigger number for the same car. Pick mpg UK, not mpg US.

FAQ

Why is a lower L/100 km better?

It is consumption, not distance per litre. mpg and km/L run the other way.

Can I convert kWh per 100 km?

No. That is an EV figure. Use the energy converter for kWh, not this page.

Does this know my tank size?

No. Combine with the volume converter if you want litres from a tank and a range.

Is 23.5 mpg US really 10 L/100 km?

Yes to the digits this page prints. It uses the exact US gallon and international mile.

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Related formats

Last reviewed 16 August 2026. Report a problem. Reports do not include your input.