How to calculate fuel efficiency
L/100km = 235.215 ÷ MPG (US) · L/100km = 282.481 ÷ MPG (UK)
Worked example. 35 MPG (US) equals: 6.72 L/100km.
Example inputs — Fuel efficiency: 35; From: MPG (US); To: L/100km. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Note the direction flip: higher MPG is better, but lower L/100km is better. UK gallons are larger than US gallons, so UK MPG numbers run higher.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
Why is UK MPG different?
The imperial gallon is 4.546 liters vs 3.785 liters for the US gallon — about 20% bigger.