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Unit Conversion & Everyday Life

Fuel Economy Converter

Convert fuel economy between mpg (US and imperial), litres per 100 km, km per litre and miles per litre.

Your inputs

Results

30 mpg (US) in L/100 km

7.8404861111 L/100 km

Conversion type
Exact (from defined constants; display rounded to 12 significant figures)

✓Exact calculation — rounded only for display

30 mpg (US) in all fuel economy units5 rows
UnitValue
Kilometres per litre (km/L)12.7543112229
Litres per 100 km (L/100 km)7.8404861111
Miles per US gallon (mpg (US))30
Miles per imperial gallon (mpg (imp))36.0284977651
Miles per litre (mi/L)7.9251615707

What this calculator does

Fuel economy is expressed as distance per volume (mpg, km/L) or volume per distance (L/100 km). The two are reciprocals, so conversions are not linear.

Formula and method

km/L = 100 ÷ (L/100 km); 1 mpg (US) = 1.609344 km ÷ 3.785411784 L ≈ 0.4251 km/L

Worked example

Calculated by this tool with its default inputs:

Inputs

  • Value: 30
  • From: Miles per US gallon (mpg (US))
  • To: Litres per 100 km (L/100 km)

Results

  • 30 mpg (US) in L/100 km: 7.8404861111 L/100 km
  • Conversion type: Exact (from defined constants; display rounded to 12 significant figures)

How to read the results

Lower L/100 km and higher mpg both mean better economy.

Assumptions and limitations

  • US and imperial gallons differ, so US and UK mpg figures are not comparable directly.
  • Constants follow NIST SP 811 and the SI Brochure. Conversions marked exact follow from defined values; display is rounded to 12 significant figures.

Questions

What is 30 mpg in L/100 km?

About 7.84 L/100 km (US gallons).

Sources

Methodology and verification

Result type
Exact mathematical calculation (rounded only for display)
Formula version
1.0
Automated verification
8 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

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