What this tool does
Converts between US MPG, UK MPG (imperial), L/100km, and km/L simultaneously.
Converter and calculator
Fuel Economy Converter
Convert fuel economy between MPG (US), MPG (UK), L/100km, and km/L. Covers all common formats used in the US, UK, Europe, and Asia.
Complete guide
How to use Fuel Economy Converter
Unit converters guide for fuel economy converter users.
Fuel economy units are confusing internationally. The US and UK both say 'MPG' but they aren't the same — the US gallon is smaller than the UK imperial gallon. European and Asian markets use litres per 100 kilometres (L/100km). This converter handles all of them.
US vs UK MPG
US gallon = 3.785 L. UK gallon = 4.546 L. A car rated at 30 US MPG = 36 UK MPG = 7.84 L/100km.
How to use it
Enter a value in any unit. All other fields update instantly.
Quick checklist
- US MPG ≠ UK MPG — UK MPG is ~20% higher for the same car.
- Lower L/100km = better economy. Higher MPG = better economy.
- 1 US MPG = 0.4251 km/L = 235.2 L/100km (inverse relationship).
- Electric vehicle efficiency is measured in miles/kWh or kWh/100km, not covered here.
Answers
Fuel Economy Converter FAQs
Why is UK MPG higher than US MPG for the same car?
A UK gallon (imperial) = 4.546 litres. A US gallon = 3.785 litres. The same fuel quantity goes further in 'UK miles per gallon' terms.
How do I convert L/100km to MPG?
US MPG = 235.21 ÷ L/100km. Example: 7 L/100km = 235.21 ÷ 7 = 33.6 US MPG.
What is a good fuel economy?
For petrol/gas cars: under 7 L/100km (over 34 US MPG) is efficient. For SUVs/trucks, under 10 L/100km (over 24 US MPG) is average.
Does this cover km/L?
Yes. km/L is used in Japan and some Asian markets. It is the inverse of L/km — a higher number means better economy.