Fuel economy converter
Fuel economy Converter – 4 Units, Exact Factors
1 mile per US gallon = 235.21 litres per 100 km
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- 1 mpg (US) = 235.21 L/100 km
- 5 mpg (US) = 47.043 L/100 km
- 10 mpg (US) = 23.521 L/100 km
- 25 mpg (US) = 9.4086 L/100 km
- Miles per US gallonmpg (US)
- Miles per imperial gallon (UK)mpg (UK)
- Litres per 100 kmL/100 km
- Kilometres per litrekm/L
- Miles per US gallon1mpg (US)
- Miles per imperial gallon (UK)1.2009mpg (UK)
- Litres per 100 km235.21L/100 km
- Kilometres per litre0.42514km/L
About fuel economy conversions
Litres per 100 km is a consumption figure (lower is better) while mpg is an economy figure (higher is better), so the conversion is a reciprocal, not a simple multiplication.
US customary and British imperial units with the same name differ in size. Each is labelled US or UK in the unit list.
Common fuel economy conversions
Fuel economy units explained
| Unit | System | Definition and notes |
|---|---|---|
| Mile per US gallon (mpg (US)) | US customary | 1 mpg (US) ≈ 0.42514371 km/L |
| Mile per imperial gallon (mpg (UK)) | British imperial | 1 mpg (UK) ≈ 0.35400619 km/L |
| Litre per 100 km (L/100 km) | metric (non-SI) | km/L = 100 ÷ L/100 km |
| Kilometre per litre (km/L) | metric (non-SI) | Base unit |
Miles per US gallon to litres per 100 km conversion table
| Miles per US gallon (mpg (US)) | Litres per 100 km (L/100 km) |
|---|---|
| 10 mpg (US) | 23.521 L/100 km |
| 15 mpg (US) | 15.681 L/100 km |
| 20 mpg (US) | 11.761 L/100 km |
| 25 mpg (US) | 9.4086 L/100 km |
| 30 mpg (US) | 7.8405 L/100 km |
| 35 mpg (US) | 6.7204 L/100 km |
| 40 mpg (US) | 5.8804 L/100 km |
| 45 mpg (US) | 5.227 L/100 km |
| 50 mpg (US) | 4.7043 L/100 km |
| 60 mpg (US) | 3.9202 L/100 km |
| 70 mpg (US) | 3.3602 L/100 km |
Frequently asked questions
Which fuel economy units can I convert?
miles per US gallon (mpg (US)), miles per imperial gallon (mpg (UK)), litres per 100 km (L/100 km), kilometres per litre (km/L).
How accurate are the results?
Every unit is stored with its exact defining factor (NIST SP 811, NIST Handbook 44 or the BIPM SI Brochure). Calculations use double-precision arithmetic and are rounded only for display, to 5 significant figures by default (trailing zeros dropped, so 1 km shows as 1000 m). You can choose Auto (up to 10 digits), fixed decimals or more significant figures, or switch to scientific or engineering notation.
Why do US and UK (imperial) units give different answers?
Several units share a name but not a size. A US gallon is exactly 3.785411784 L while an imperial gallon is exactly 4.54609 L; a US fluid ounce is about 29.57 mL and a UK fluid ounce about 28.41 mL. Units are labelled US or UK throughout so you can pick the right one.