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Fuel Economy Converter

Convert US MPG, UK (imperial) MPG, and L/100km fuel economy instantly in your browser.

Tool workspace

MPG and L/100km are inverse: higher MPG means lower L/100km. US MPG uses the US gallon; UK MPG uses the imperial gallon.

Conversion runs in your browser among US MPG, UK MPG, and L/100km. Values are not sent to our servers.

Converted values

How it works

Enter a value and choose the source unit: miles per gallon (US), miles per gallon (UK / imperial), or litres per 100 kilometres (L/100km). MPG and L/100km are inverse: L/100km = K / MPG.

US MPG uses the US gallon (factor ≈ 235.215). UK MPG uses the imperial gallon (factor ≈ 282.481). Labels keep US and UK distinct so the gallon size is never ambiguous.

Results update as you type (light debounce). Empty input clears the results—no error. Zero, negative, or non-numeric input shows a validation message (conversion is undefined at zero).

Displayed values keep up to 10 decimal places and drop trailing zeros. Use Sample for 25 US MPG.

Examples

  • 25 US MPG → ≈ 9.4086 L/100km
  • 25 UK MPG → ≈ 11.2992 L/100km
  • 10 L/100km → ≈ 23.5215 US MPG
  • 10 L/100km → ≈ 28.2481 UK MPG

Privacy

Privacy: this tool processes values locally in your browser. We do not log or store what you enter. Login is not required.

FAQ

Is my value uploaded to a server?

No. Conversion runs entirely in your browser. Values are not sent to Every Tools.

What is the difference between US MPG and UK MPG?

Both measure miles per gallon, but the gallon size differs. The US gallon is 3.785411784 L; the UK (imperial) gallon is 4.54609 L. The same numeric MPG therefore maps to different L/100km values.

Why is MPG ↔ L/100km inverse?

MPG is distance per volume; L/100km is volume per distance. Doubling MPG halves L/100km (for the same gallon definition).

Why can’t I enter zero or a negative value?

Division by zero is undefined, and negative fuel economy is not meaningful for this converter.

Do I need an account?

No. All published tools work for guests without login.

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