US MPG to litres per 100 km
- Input
- 30 MPG (US) to L/100 km.
- Working
- L/100 km = 235.214583 ÷ 30 = 7.8405. In km/L: 100 ÷ 7.8405 = 12.75.
- Result
- 30 MPG (US) = 7.84 L/100 km = 12.75 km/L
Fuel Consumption Converter
Convert MPG to litres per 100 km and back for US and imperial gallons — the inverse conversion explained, in your browser. Runs entirely in your browser — your numbers never leave this device.
Miles per US gallon → Litres per 100 km
7.840486 L/100 km
In every unit: 30 MPG (US) · 36.028498 MPG (imp) · 7.840486 L/100 km · 12.754311 km/L
How it works
L/100 km = 235.214583 ÷ MPG (US); L/100 km = 282.480936 ÷ MPG (imperial); km/L = 100 ÷ (L/100 km)
| MPG (US) | L/100 km | km/L |
|---|---|---|
| 15 | 15.68 | 6.38 |
| 20 | 11.76 | 8.50 |
| 25 | 9.41 | 10.63 |
| 30 | 7.84 | 12.75 |
| 35 | 6.72 | 14.88 |
| 40 | 5.88 | 17.01 |
| 50 | 4.70 | 21.26 |
Fuel consumption is the conversion people fumble most, because the two systems are reciprocals, not just different-sized units. Miles per gallon measures distance per unit of fuel — bigger is better. Litres per 100 km measures fuel per fixed distance — bigger is worse. Converting therefore means dividing a constant by the starting figure, not multiplying by a factor, and the constant depends on the gallon: L/100 km = 235.214583 ÷ MPG for US gallons and 282.480936 ÷ MPG for imperial gallons.
Those constants come directly from the definitions: a mile is 1.609344 km and a US gallon is 3.785411784 L, so travelling 100 km at a given MPG uses 100 ÷ (MPG × 1.609344) gallons, which is 235.214583 ÷ MPG litres. Swapping in the imperial gallon of 4.54609 L gives the 282.480936 constant. The same car therefore shows two different MPG figures — a consumption of 8.0 L/100 km is 29.40 MPG in the US and 35.31 MPG in the UK — and neither is wrong.
Kilometres per litre, used in some markets, sits between the two ideas: it measures distance per unit of fuel like MPG, but in metric units, and it converts by km/L = 100 ÷ (L/100 km). So 8.0 L/100 km is 12.5 km/L. The correspondence table lets you read across all three systems at the consumption levels cars actually achieve.
Worked examples
Litres per 100 km to US MPG
- Input
- 8.0 L/100 km to MPG (US).
- Working
- MPG = 235.214583 ÷ 8.0 = 29.4018.
- Result
- 8.0 L/100 km = 29.40 MPG (US)
Imperial MPG to litres per 100 km
- Input
- 40 MPG (imperial) to L/100 km.
- Working
- L/100 km = 282.480936 ÷ 40 = 7.0620. In km/L: 100 ÷ 7.0620 = 14.16.
- Result
- 40 MPG (imperial) = 7.06 L/100 km = 14.16 km/L
Frequently asked questions
Why do I divide instead of multiply to convert MPG?
Because the measures are inverses. MPG is distance divided by fuel; L/100 km is fuel divided by distance (scaled to 100 km). Turning one into the other flips the fraction, which is why the formula is a constant divided by your figure — and why doubling MPG halves the L/100 km figure rather than doubling anything.
Why is UK MPG higher than US MPG for the same car?
Because the imperial gallon (4.54609 L) is larger than the US gallon (3.785411784 L), so a car travels further on each imperial gallon. The same 8.0 L/100 km converts to 235.214583 ÷ 8.0 = 29.40 MPG (US) and 282.480936 ÷ 8.0 = 35.31 MPG (imperial). Always note which gallon an MPG figure uses.
Is a lower L/100 km figure better?
Yes — the opposite of MPG. Litres per 100 km counts fuel burned over a fixed distance, so 6.0 L/100 km uses less fuel than 9.0 L/100 km. In MPG terms that same improvement reads as going from about 26.14 MPG to about 39.20 MPG (US), using 235.214583 ÷ 9 and ÷ 6.
How do I convert L/100 km to km per litre?
Divide 100 by the L/100 km figure: km/L = 100 ÷ (L/100 km). So 6.5 L/100 km is 100 ÷ 6.5 = 15.38 km/L, and it converts to US MPG as 235.214583 ÷ 6.5 = 36.19 MPG. The three systems are all one division away from each other once you fix the gallon.
What does 235.214583 represent?
It is 100 km expressed through the conversion chain: 100 ÷ 1.609344 (miles in 100 km) × 3.785411784 (litres in a US gallon), which gives 62.1371 × 3.785411784 = 235.214583. The imperial constant, 282.480936, is the same chain with 4.54609 litres per gallon instead.
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