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Fuel Economy Converter: km/L, L/100 km, MPG (US and UK) and EV MPGe

Convert a fuel economy figure between kilometres per litre, litres per 100 km, miles per US gallon and miles per imperial gallon.

Maintained by Hirantha Sandaruwan Lakshan. Updated 13 October 2026.

About this tool

A second mode converts electric vehicle figures: kWh per 100 km, kilometres per kWh, miles per kWh and MPGe. The two kinds of unit run in opposite directions, so the page shows every unit in one table and handles zero without dividing by it.

How it works

Kilometres per litre says how far one litre takes you, so a bigger number is better. Litres per 100 km says how much fuel 100 km needs, so a smaller number is better. They are reciprocals: L/100 km = 100 divided by km/L, and km/L = 100 divided by L/100 km. It is not a simple multiple. 10 km/L is 10 L/100 km, but 20 km/L is 5 L/100 km. Zero has no reciprocal, so 0 km/L (infinite litres per 100 km) and 0 L/100 km (infinite km/L) are shown as not defined instead of a number.

A mile is exactly 1.609344 km. A US gallon is exactly 3.785411784 litres (231 cubic inches). An imperial gallon is exactly 4.54609 litres. So miles per US gallon = km/L x 3.785411784 / 1.609344, which is km/L x 2.352146, and miles per imperial gallon = km/L x 2.824809. NIST gives the same rule in SP 811: L/100 km = 235.215 divided by mpg (US). A UK car quoted at 40 mpg is not a 40 mpg car by US figures: 40 imperial mpg is 7.06 L/100 km, 14.16 km/L or 33.31 US mpg, because the imperial gallon is 20% bigger than the US one.

Electric vehicles use energy, not fuel volume. kWh per 100 km = 100 divided by km per kWh, and Wh per km is the kWh per 100 km figure times 10. MPGe is the US EPA's way to compare: the regulations treat one US gallon of gasoline as 33.705 kWh of electricity (40 CFR 600.002), so MPGe = 33.705 x miles per kWh, and a car at 100 MPGe uses 33.705 kWh per 100 miles. The EV mode also shows the petrol-car figures that use the same energy per mile. That compares energy at the plug with energy in the fuel only; it says nothing about running cost, charging losses outside the car or emissions.

In Sri Lanka, fuel economy is commonly quoted in kilometres per litre. The Daily FT's 2017 round-the-island test of a Mercedes-Benz Vito, for example, reported an average of 20.8 km per litre over the whole trip. Brochures from Europe often use L/100 km and US ones use mpg, so convert before you compare two cars. Real consumption depends on traffic, load, air conditioning, tyre pressure and driving style. For the price of a trip, use the fuel cost calculator.

Worked examples

A car that does 12 km per litre

L/100 km = 100 divided by 12 = 8.333. In miles per gallon that is 12 x 2.352146 = 28.23 mpg (US) and 12 x 2.824809 = 33.90 mpg (imperial).

A US car rated 35 mpg

L/100 km = 235.2146 divided by 35 = 6.72. In km/L that is 35 x 0.425144 = 14.88 km per litre. Check: 100 divided by 6.72 = 14.88.

Your own tank-to-tank figure

Fill the tank, reset the trip meter, drive, then fill up again. If you drove 420 km and the pump took 35 litres, you got 420 divided by 35 = 12 km per litre, or 8.33 L/100 km.

An EV using 15 kWh per 100 km

That is 6.667 km per kWh, 150 Wh/km, 4.142 miles per kWh and 24.14 kWh per 100 miles. In MPGe it is 4.1425 x 33.705 = 139.6 MPGe, the same energy per mile as a petrol car doing 139.6 mpg (US).

Common fuel consumption figures in other units

L/100 kmkm per litrempg (US)mpg (imperial)
42558.870.62
52047.0456.5
616.6739.247.08
714.2933.640.35
812.529.435.31
911.1126.1331.39
101023.5228.25
128.33319.623.54
156.66715.6818.83

Frequently asked questions

How do I convert L/100 km to km per litre?

Divide 100 by the L/100 km figure. 8 L/100 km is 100 divided by 8 = 12.5 km per litre. The same formula works the other way: 12.5 km per litre is 100 divided by 12.5 = 8 L/100 km.

How do I convert km per litre to miles per gallon?

Multiply by 2.352146 for US gallons or by 2.824809 for imperial gallons. 12 km per litre is 28.23 mpg (US) or 33.90 mpg (imperial). To go back, divide by the same factors.

Why are UK and US miles per gallon different?

The gallons are different sizes. A US gallon is 3.785 litres and an imperial gallon is 4.546 litres, so an imperial gallon is 1.2009 US gallons. The same car has an mpg figure that is 20% higher in imperial gallons than in US gallons.

What is MPGe and how is it calculated?

MPGe is miles per gallon of gasoline equivalent. The US EPA treats one US gallon of gasoline as 33.705 kWh of electricity, so MPGe = 33.705 divided by the kWh used per mile. A car using 0.33705 kWh per mile (33.705 kWh per 100 miles) rates 100 MPGe. It compares energy use, not running costs.

What does 0 km/L or 0 L/100 km mean?

Neither has a sensible reciprocal. 0 km/L means the vehicle goes nowhere on a litre, so L/100 km would be infinite. 0 L/100 km means no fuel is used, so km/L would be infinite. The tool shows these as not defined instead of dividing by zero.

Is kWh per 100 km the same as Wh per km?

Not the same number: Wh per km is ten times kWh per 100 km, because 1 kWh is 1,000 Wh and 100 km is 100 times 1 km. 15 kWh/100 km is 150 Wh/km.

Will I get the brochure figure?

Usually not exactly. Brochure figures come from a test with set conditions. Your result depends on traffic, load, hills, air conditioning, speed and tyre pressure. Work out your own figure from a full tank to a full tank and convert that.

Sources & references

Updated Oct 13, 2026