Unit Converters
Convert MPG (US & UK), L/100km and km/L — with the direction handled correctly.
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30.00 US MPG equals
| US MPG | UK MPG | L/100km | km/L |
|---|---|---|---|
| 15 | 18.0 | 15.68 | 6.38 |
| 20 | 24.0 | 11.76 | 8.50 |
| 25 | 30.0 | 9.41 | 10.63 |
| 30 | 36.0 | 7.84 | 12.75 |
| 40 | 48.0 | 5.88 | 17.01 |
| 50 | 60.0 | 4.70 | 21.26 |
| 60 | 72.1 | 3.92 | 25.51 |
Watch the direction. MPG and km/L are "distance per fuel" — higher is better. L/100km is "fuel per distance" — lower is better. That's why L/100km is the reciprocal: L/100km = 100 ÷ (km/L).
US and UK gallons differ: an imperial (UK) gallon is ~20% larger, so 30 UK MPG is noticeably thirstier than 30 US MPG. Always check which gallon a figure uses.
Enter your fuel-economy figure.
Choose the unit it's in — US MPG, UK MPG, L/100km or km/L — under "From".
Pick your target unit in "To", or read all four at once in the grid.
Use the reference table to compare common values, and remember: for MPG and km/L higher is better, for L/100km lower is better.
Fuel economy is uniquely confusing to convert because different countries don't just use different units — they measure the opposite thing. The US and UK quote miles per gallon, where a bigger number is better. Most of the world quotes litres per 100 km, where a smaller number is better. Some places use kilometres per litre. This converter moves cleanly between all of them and, crucially, gets the direction right, because L/100km is the reciprocal of the others, not a simple multiple.
That reciprocal relationship is where mistakes happen. If a car does 50 km on a litre... no, that's not how L/100km works — you invert it: 100 ÷ (km per litre). This tool does the inversion for you, so converting 40 US MPG gives you the correct 5.9 L/100km rather than a nonsensical scaled figure. It also keeps US and UK gallons separate, which matters a lot: an imperial gallon is about 20% larger than a US gallon, so the same "30 MPG" describes a noticeably more efficient car in UK terms than in US terms.
Whether you're comparing a US-spec car against a European one, translating a road-trip's efficiency, or just making sense of a spec sheet, the converter shows all four measures at once with a reference table of common values. As always the maths is exact, precision is adjustable, and a plain-language note keeps the "higher is better" versus "lower is better" distinction front and centre so you never compare two cars the wrong way round.
Comparing the fuel economy of a US-spec car against a European or Asian model quoted in L/100km.
Translating a rental car's efficiency abroad into the units you understand.
Working out a road trip's real fuel consumption from distance and litres used.
Reconciling US MPG and UK MPG figures, which look similar but aren't.
Higher MPG and km/L mean a more efficient car; lower L/100km means a more efficient car. Never rank cars by the raw number without checking which unit it is.
UK MPG figures always look better than US MPG for the same car because the imperial gallon is larger — about 1.2× the US gallon.
For a quick check, 235 ÷ US MPG ≈ L/100km (e.g. 235 ÷ 40 ≈ 5.9). The tool uses the exact factors.
Converting L/100km as if it scaled directly with MPG. It's inversely related — you divide, not multiply — which this tool handles automatically.
Comparing a US MPG figure with a UK MPG figure head-to-head. Convert them to the same unit first, or the ~20% gallon difference will mislead you.
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