Online Tool Store
Mileage Unit Converter
Convert fuel economy between MPG (US), MPG (UK/Imperial), L/100km, and km/L. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
US and UK/Imperial gallons differ in size — MPG (UK) values are not directly comparable to MPG (US) without conversion.
How it works
- Enter your fuel economy value and its unit.
- See the equivalent in MPG (US), MPG (UK), L/100km, and km/L.
The formula
L/100km = (gallon size in liters ÷ (MPG × 1.609344 km/mi)) × 100
km/L = 100 ÷ L/100km
US gallon = 3.785411784 L, UK gallon = 4.54609 L
FAQ
Why are US and UK MPG different for the same value?
A US gallon (3.785 liters) is smaller than a UK/Imperial gallon (4.546 liters) — the same car, the same fuel economy, produces a higher MPG number in the UK simply because each "gallon" covers more distance-worth of fuel.
Why does L/100km work backwards from MPG?
MPG is "distance per unit fuel" — higher is more efficient. L/100km is "fuel per unit distance" — lower is more efficient. That's why the conversion between them is an inverse relationship, not a simple multiplier.
What is km/L used for?
A simpler, more intuitive metric alternative to L/100km, common in some regions — how many kilometers you travel per liter of fuel, same "higher is better" direction as MPG.
Is my data uploaded anywhere?
No — every calculation happens locally in your browser. Nothing is sent to a server.
How we compare
| Feature | Online Tool Store | Manual formula lookup | Car spec comparison sites |
|---|---|---|---|
| Distinguishes US vs UK gallons | ✓ | Easy to mix up by accident | Varies by site |
| All four units at once | ✓ | Convert one pair at a time | Usually just one unit shown |
For comparing a car's spec sheet between regions using different units, this avoids the US/UK gallon mix-up that trips up manual conversions.