Fuel Economy Calculator
Convert distance and fuel into MPG, L/100km and km/L.
Enter distance and fuel used to compute fuel economy in US MPG, UK MPG, L/100km and km/L. Mix and match input units freely.
Common use cases
- Track real-world fuel economy from tank-to-tank
- Compare US and UK MPG ratings (UK gallons are bigger)
- Convert manufacturer L/100km specs to MPG before buying
- Estimate trip cost from distance and known economy
Frequently asked questions
Why is UK MPG higher than US MPG?▾
UK gallons are 4.546 L vs US 3.785 L — about 20% larger. Same car shows higher MPG in UK terms.
L/100km lower is better?▾
Yes — it's consumption (lower = uses less fuel per distance). MPG is the inverse: higher = better.
Convert MPG to L/100km?▾
L/100km = 235.215 / MPG (US). So 30 MPG ≈ 7.84 L/100km.