MPG Imperial vs US
Convert MPG between US gallons and Imperial gallons.
About MPG Imperial vs US
Because the imperial gallon is bigger, the same real fuel economy reads as roughly 20 percent higher in miles per imperial gallon. UK and US figures are frequently misread as equal, which can badly skew comparisons of fuel economy between markets.
Formula
MPG Imperial vs US
MPG imperial = MPG US x 1.20095 (one imperial gallon is 20% larger)
- imperial gallon
- Equals about 4.546 liters, versus 3.785 liters for the US gallon
Worked example
With the default values below, MPG Imperial vs US returns MPG (US gal) of 30.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- MPG valueminimum 0.001 mpg
- 30 mpg
- Given systemone of US MPG, Imperial MPG
- US MPG
Results
- MPG (US gal)
- 30.0
- MPG (Imperial gal)
- 36.0
- Liters per 100 km
- 7.84 L/100km
Step by step
- 1Values used
- 2MPG Imperial vs US
- 3MPG (US gal)= 30.0
- 4MPG (Imperial gal)= 36.0
- 5Liters per 100 km= 7.84 L/100km
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is MPG Imperial vs US calculated?
MPG imperial = MPG US x 1.20095 (one imperial gallon is 20% larger) Because the imperial gallon is bigger, the same real fuel economy reads as roughly 20 percent higher in miles per imperial gallon.
Why does MPG Imperial vs US matter?
UK and US figures are frequently misread as equal, which can badly skew comparisons of fuel economy between markets.
What values do I need to enter?
This calculator takes 2 inputs: MPG value, Given system. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.