MPG to L/100km Converter
Convert miles per gallon to litres per 100 km and back, for both US and UK gallons, plus km/L.
Type a fuel-economy figure — every other unit is converted as you type.
- L/100km
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- km/L
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- MPG (US)
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- MPG (UK)
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Quick reference: MPG to L/100km
| MPG | L/100km (US gallon) | L/100km (UK gallon) |
|---|---|---|
| 15 | 15.68 | 18.83 |
| 20 | 11.76 | 14.12 |
| 25 | 9.41 | 11.30 |
| 30 | 7.84 | 9.42 |
| 35 | 6.72 | 8.07 |
| 40 | 5.88 | 7.06 |
| 45 | 5.23 | 6.28 |
| 50 | 4.70 | 5.65 |
How it works
Miles per gallon and litres per 100 km are inverse measures: a higher MPG is better, a lower
L/100km is better. Converting between them is a single division. With a
US gallon the conversion is
L/100km = 235.214583 ÷ MPG; with a UK (imperial) gallon it is
L/100km = 282.480936 ÷ MPG. Those constants come straight from the exact legal
definitions — 1 US gallon = 3.785411784 L, 1 imperial gallon = 4.54609 L and 1 mile =
1.609344 km — so (litres per gallon ÷ km per mile) × 100 gives the factor. The
same division runs the other way, which is why 30 US MPG is 7.84 L/100km and 7.84 L/100km is
30 US MPG again.
The UK gallon is about 20% larger than the US gallon, so the same car is always quoted with a
higher MPG figure in Britain than in America: 30 US MPG equals roughly 36 UK MPG. Pick the
right gallon before you compare two cars. This page also shows km/L, used in Japan, India and
much of Latin America, which is simply 100 ÷ (L/100km). Everything is calculated
in your browser with plain JavaScript — no uploads, no sign-up, no ads and nothing is sent
anywhere.
Frequently asked questions
How do you convert MPG to L/100km?
Divide 235.214583 by the MPG figure when it uses US gallons, or 282.480936 when it uses UK (imperial) gallons. So 30 US MPG is 235.214583 ÷ 30 = 7.84 L/100km, and 30 UK MPG is 282.480936 ÷ 30 = 9.42 L/100km. The same division works in reverse, because the two units are inverses of each other.
Why do US and UK MPG figures differ for the same car?
An imperial gallon is 4.54609 litres while a US gallon is 3.785411784 litres — about 20% larger. A car that travels 30 miles on a US gallon travels roughly 36 miles on the bigger UK gallon, so its UK MPG number is higher even though the fuel consumption is identical. Always check which gallon a quoted MPG figure uses before comparing cars.
What is 30 MPG in L/100km?
30 MPG on US gallons is 7.84 L/100km (12.75 km/L). If the 30 MPG figure is British, it is 9.42 L/100km (10.62 km/L). Enter the value in the converter and pick the matching gallon to see both, along with km/L.