mpg to L/100km converter

Fuel economy runs backwards between the two systems — higher mpg means lower L/100km — and US and UK gallons differ by 20%. This converts US mpg both ways and shows the UK figure and km/L.

Litres per 100 km

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Litres per 100 km—
UK mpg (imperial gallon)—
Kilometres per litre—
Miles per litre—
US mpg—

Miles per gallon (US) to litres per 100 km

Miles per gallon (US)Litres per 100 km
10 mpg23.52 L/100km
15 mpg15.68 L/100km
18 mpg13.07 L/100km
20 mpg11.76 L/100km
22 mpg10.69 L/100km
25 mpg9.41 L/100km
28 mpg8.4 L/100km
30 mpg7.84 L/100km
32 mpg7.35 L/100km
35 mpg6.72 L/100km
38 mpg6.19 L/100km
40 mpg5.88 L/100km
45 mpg5.23 L/100km
50 mpg4.7 L/100km
55 mpg4.28 L/100km
60 mpg3.92 L/100km
70 mpg3.36 L/100km
80 mpg2.94 L/100km
100 mpg2.35 L/100km

Litres per 100 km to miles per gallon (US)

Litres per 100 kmMiles per gallon (US)
3 L/100km78.4 mpg
3.5 L/100km67.2 mpg
4 L/100km58.8 mpg
4.5 L/100km52.27 mpg
5 L/100km47.04 mpg
5.5 L/100km42.77 mpg
6 L/100km39.2 mpg
6.5 L/100km36.19 mpg
7 L/100km33.6 mpg
7.5 L/100km31.36 mpg
8 L/100km29.4 mpg
9 L/100km26.13 mpg
10 L/100km23.52 mpg
12 L/100km19.6 mpg
15 L/100km15.68 mpg
20 L/100km11.76 mpg

Related calculators

Length Weight Temperature Volume Area Speed

Two units that run in opposite directions

Miles per gallon measures distance per fuel; litres per 100 km measures fuel per distance. So they are reciprocals, not multiples: doubling mpg halves L/100km. With the US gallon of 3.785411784 L and the mile of 1.609344 km, the conversion is L/100km = 235.2146 ÷ mpg, and the same formula runs backwards. The imperial gallon is 4.54609 L, so UK mpg figures are 20% higher for the same car: 30 mpg US is 36 mpg UK.

L/100km = 235.2146 ÷ mpg (US)   |   L/100km = 282.4809 ÷ mpg (UK)   |   km/L = 100 ÷ L/100km

Why the reciprocal matters

Because the scale is curved, equal mpg gains are not equal fuel savings. Going from 15 to 20 mpg saves 3.9 L per 100 km; going from 40 to 45 saves only 0.65. Per-distance units make that obvious, which is why Europe, Canada, Australia and most fleet managers prefer L/100km, and why US window stickers now also show gallons per 100 miles. Japan and parts of Asia quote km/L instead, which is simply 100 ÷ L/100km.

Reference points

A large SUV at 18 mpg US uses 13.1 L/100km; a typical sedan at 30 mpg, 7.8; an efficient hybrid at 50 mpg, 4.7. The fuel cost calculator turns any of these into money for a trip.

Frequently asked questions

What is 30 mpg in L/100km?
30 US mpg is 7.84 L/100km, or 12.75 km/L. In UK mpg (imperial gallon) the same car is 36.0 mpg.
How do I convert L/100km to mpg?
Divide 235.21 by the L/100km figure for US mpg, or 282.48 for UK mpg. 8 L/100km is 29.4 mpg US or 35.3 mpg UK.
Why are UK mpg figures higher than US ones?
The imperial gallon is 4.546 litres against the US gallon's 3.785, 20% more fuel, so the same car goes 20% further per gallon: US mpg × 1.201 = UK mpg.
What is a good L/100km?
Roughly: under 5 is excellent (hybrids, small diesels), 6–8 is typical for a modern petrol car, 10–13 is a large SUV or pickup. Electric cars use kWh/100 km instead.
How do I convert mpg to km per litre?
Multiply US mpg by 0.4251 (1.609344 ÷ 3.785411784). 30 mpg is 12.75 km/L; 40 mpg is 17.0 km/L.

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