Fuel economy converter
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.
1 mile per US gallon = 235.21 litres per 100 km
How it’s calculated
L/100 km = 235.2145833 ÷ mpg (US)
- These units are inversely related (one measures amount per distance, the other distance per amount), so divide 235.2145833 by the value.
- Doubling one halves the other. A value of zero has no finite equivalent.
- 1 mpg (US) = 235.2145833 L/100 km · 1 L/100 km = 235.2145833 mpg (US)
Show worked solutionFactor, unit cancellation and rounding, step by step
These units are inversely related
One unit measures “per distance” and the other “per volume” or “per time”, so the conversion divides instead of multiplying. Go through km/L. Source: Derived from exact length, volume and time definitions (NIST SP 811 / Handbook 44).
Convert to km/L
Convert km/L to L/100 km
L/100 km = 100 ÷ km/L
Round the answer
Rounded to 5 significant figures.
Answer: 235.21 L/100 km
1 mpg (US) in other units
Batch convert mpg (US) → L/100 km
- 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
Common fuel economy conversions
Fuel economy units and exact definitions
| Unit | System | Definition |
|---|---|---|
| Mile per US gallon (mpg (US)) | US customary | 1 mpg (US) = 0.4251437074 km/L |
| Mile per imperial gallon (mpg (UK)) | British imperial | 1 mpg (UK) = 0.3540061899 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.