Fuel Economy Converter
Convert miles per gallon (US and UK), kilometers per liter and liters per 100 kilometers.
· CalcFlow Editorial
1 mpg (US) = 235.21458 L/100km
Results shown are estimates for informational purposes only. Nothing on CalcFlow is financial, tax, legal, or medical advice. Always consult a qualified professional before making important decisions.
Common Fuel Economy Conversions
| Miles per US gallon | Liters per 100 km | Miles per UK gallon | Kilometers per liter |
|---|---|---|---|
| 5 mpg (US) | 47.042917 | 6.0047496 | 2.1257185 |
| 8 mpg (US) | 29.401823 | 9.6075994 | 3.4011497 |
| 10 mpg (US) | 23.521458 | 12.009499 | 4.2514371 |
| 15 mpg (US) | 15.680972 | 18.014249 | 6.3771556 |
| 20 mpg (US) | 11.760729 | 24.018999 | 8.5028741 |
| 25 mpg (US) | 9.4085833 | 30.023748 | 10.628593 |
| 30 mpg (US) | 7.8404861 | 36.028498 | 12.754311 |
| 40 mpg (US) | 5.8803646 | 48.037997 | 17.005748 |
| 50 mpg (US) | 4.7042917 | 60.047496 | 21.257185 |
Popular Fuel Economy Conversions
Formula
km/L = mpg x 1.609344 / 3.785411784 (US) ; L/100km = 100 / (km/L) ; mpg and L/100km are reciprocalsUnderstanding Fuel Economy Conversion
Fuel economy is expressed two opposite ways. Miles per gallon and kilometers per liter measure distance per unit of fuel, so higher is better. Liters per 100 kilometers measures fuel per distance, so lower is better, and it is the reciprocal of the others. US and UK gallons differ by about 20 percent, so a UK mpg figure is higher than the US figure for the same car.
Tips and Best Practices
- 1Divide 235.215 by the US mpg figure to get L/100km, and the other way round.
- 2Divide 282.481 by the UK mpg figure to get L/100km.
- 3Compare cars in the same unit, ideally L/100km, to see fuel saved per distance.
Real-World Example
A car rated at 30 mpg (US) uses 235.215 / 30 = 7.84 L/100km. The same car in UK mpg is about 36 mpg.
Common Mistakes to Avoid
- Comparing a US mpg figure with a UK mpg figure directly.
- Assuming a 10 mpg improvement saves the same fuel from 15 to 25 mpg as from 40 to 50 mpg (it does not).
- Dividing instead of using the reciprocal when switching between mpg and L/100km.
How to Use
- Pick the unit you have in the left selector and the unit you want in the right selector.
- Type a number in either box; the other box updates instantly.
- Use the swap button to reverse the direction and Copy result to copy the answer.
Frequently Asked Questions
How do I convert mpg to L/100km?
Is 30 mpg good?
Why are US and UK mpg different?
Sources: NIST SP 811 (mile, US gallon); UK imperial gallon = 4.54609 L.