Fuel Efficiency Calculator

Fuel efficiency measures how far a vehicle travels per unit of fuel. The UK and US use MPG (miles per gallon), while most of the world uses L/100km (litres per 100 kilometres)

The calculator uses the standard published formula for fuel efficiency. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, kilometres, miles, litres. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Note: UK and US gallons differ — 1 UK gallon = 4.546L, 1 US gallon = 3.785L. Each step in the calculation is shown so you can verify the result manually.