Convert fuel economy between L/100 km, km/L, US MPG and imperial MPG, in the right direction each time.
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5 L/100 km is 20 km/L, and 30 MPG (US) is about 7.8404861 L/100 km. Because the gallons differ, 40 MPG (UK) is only about 33.30696738 MPG (US).
Consumption and distance-per-fuel figures are reciprocals, so the conversion is a division rather than a multiplication. Everything passes through L/100 km, using about 235.21 ÷ MPG (US) and about 282.48 ÷ MPG (UK).
A lower L/100 km number is better, while a higher km/L or MPG number is better, so the same improvement looks different in each format. Official ratings come from standard tests such as WLTP or EPA cycles and rarely match real driving, and this tool converts a stated figure rather than predicting consumption.
Fuel economy is written two opposite ways. L/100 km is consumption, so a lower number is better. km/L and MPG are distance per unit of fuel, so a higher number is better. Because one is the reciprocal of the other, the conversion is a division rather than a multiplication: 5 L/100 km is 20 km/L, and 20 km/L is 5 L/100 km. Doubling km/L halves L/100 km, which is why efficiency gains look different in each format.
MPG figures depend on the gallon. A US gallon is 3.785 L and an imperial gallon is 4.546 L, so the same car has a higher MPG figure in the UK. 40 MPG (UK) is about 33.30696738 MPG (US). The tool uses about 235.21 ÷ MPG (US) and 282.48 ÷ MPG (UK) to reach L/100 km, so 30 MPG (US) is about 7.8404861 L/100 km, and 10 L/100 km is about 28.2480936 MPG (UK). Always check which gallon a review or window sticker uses.
Savings are easier to judge in L/100 km. Improving a car from 20 to 25 MPG (US) saves more fuel over the same distance than improving another from 50 to 60 MPG, even though both gain a similar number of miles per gallon. A 50 MPG (US) hybrid is about 21.2571854 km/L, and 6 L/100 km is about 39.2024305 MPG (US). Official ratings come from standard tests such as WLTP or EPA cycles and rarely match real driving exactly; use the Fuel Cost Calculator to price a trip.
| Input | Result |
|---|---|
5 L/100 km → km/L | 20 |
30 MPG (US) → L/100 km | 7.8404861 |
6 L/100 km → MPG (US) | 39.2024305 |
50 MPG (US) → km/L | 21.2571854 |
40 MPG (UK) → MPG (US) | 33.30696738 |
10 L/100 km → MPG (UK) | 28.2480936 |
Because they measure opposite things: L/100 km is the fuel consumed over a fixed distance, while km/L and MPG are the distance travelled per unit of fuel. One is the reciprocal of the other, so doubling km/L halves L/100 km — 5 L/100 km is 20 km/L, and 20 km/L is 5 L/100 km.
No. A US gallon is 3.785 L and an imperial gallon is 4.546 L, so the same car scores a higher MPG figure in the UK. 40 MPG (UK) is about 33.30696738 MPG (US), and 10 L/100 km is about 28.2480936 MPG (UK). Always check which gallon a review or window sticker uses.
Because equal MPG gains are not equal fuel savings. Improving a car from 20 to 25 MPG (US) saves more fuel over the same distance than improving another from 50 to 60 MPG. Comparing in L/100 km makes the real difference visible: a 50 MPG (US) hybrid is about 21.2571854 km/L, and 6 L/100 km is about 39.2024305 MPG (US).
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