How to convert Miles per Imperial gallon to miles per US gallon
mpg (US) = mpg (UK) × 0.832674184628989
Multiply the mpg (UK) reading by 0.832674184628989. Both sides measure distance per fuel volume, so this is a direct scale conversion. Imperial mpg uses a 4.54609 L gallon. US mpg uses a 3.785411784 L gallon.
Worked examples
30 mpg (UK) ≈ 24.98022554 mpg (US)
30 × 0.832674184628989 ≈ 24.98022554
50 mpg (UK) ≈ 41.63370923 mpg (US)
50 × 0.832674184628989 ≈ 41.63370923
Frequently asked questions
Why can a fuel-economy reading change without using less fuel?
Distance per litre and distance per gallon use different fuel-volume units. US and Imperial gallons also differ. A changed numerical reading after conversion describes the same economy.