Fuel Economy Converter
Enter a fuel economy value in any of the four common units and see it instantly converted to the other three, plus a reference table at common values.
mpg (US)
28.0
mpg (UK)
33.6
L/100 km
8.4
km/L
11.9
Reference table at common values
| mpg (US) | mpg (UK) | L/100 km | km/L |
|---|---|---|---|
| 15.0 | 18.0 | 15.7 | 6.4 |
| 20.0 | 24.0 | 11.8 | 8.5 |
| 25.0 | 30.0 | 9.4 | 10.6 |
| 30.0 | 36.0 | 7.8 | 12.8 |
| 35.0 | 42.0 | 6.7 | 14.9 |
| 40.0 | 48.0 | 5.9 | 17.0 |
| 45.0 | 54.0 | 5.2 | 19.1 |
| 50.0 | 60.0 | 4.7 | 21.3 |
| 55.0 | 66.1 | 4.3 | 23.4 |
| 60.0 | 72.1 | 3.9 | 25.5 |
How it's calculated
Every value is converted through liters per 100 km, the one internal unit every other conversion is derived from:
L/100km = 235.2146 ÷ mpg(US) = 282.4809 ÷ mpg(UK) = 100 ÷ (km/L)
Worked example
The converter's own default: 28 mpg (US) converts to:
| mpg (UK) | 33.6 |
| L/100 km | 8.4 |
| km/L | 11.9 |
Frequently Asked Questions
Why isn't mpg (US) the same number as mpg (UK)?
They use different-sized gallons: a US gallon is 3.785 liters, a UK (imperial) gallon is 4.546 liters -- about 20% larger. The same car covers the same distance on less of the larger unit, so its mpg (UK) figure is always higher than its mpg (US) figure, even though the real fuel economy hasn't changed.
Is L/100km 'lower is better' while mpg is 'higher is better'?
Yes -- L/100km measures fuel consumed per distance, so a smaller number means less fuel burned. mpg and km/L measure distance per fuel, so a bigger number means more distance per unit of fuel. Converting between them isn't linear for that reason -- doubling your mpg doesn't halve your L/100km exactly, though it's close in most everyday ranges.
What conversion factors does this use?
Exact definitional constants, not rounded approximations: a mile is 1.609344 km, a US gallon is 3.785411784 liters, and a UK gallon is 4.54609 liters (International Yard and Pound Agreement (1959); US NIST Handbook 44; UK Weights and Measures Act 1985). Every other conversion on this page is derived directly from those three numbers.
Which unit should I use when comparing cars from different countries?
L/100km is the most internationally comparable, since it's the standard in most of the world outside the US and UK and doesn't carry either country's gallon definition. Converting both cars' figures to L/100km (or km/L) sidesteps the mpg (US) vs. mpg (UK) mismatch entirely.
These are estimates; real consumption varies with driving, load and conditions. This site isn't affiliated with any vehicle manufacturer, utility, or the US Energy Information Administration -- see the Terms.