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

Page: https://hirantha.me/tools/fuel-economy-converter
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-10-13

Convert km per litre, litres per 100 km, miles per US and imperial gallon, plus EV kWh per 100 km, miles per kWh and MPGe, with exact factors.

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

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.

Common fuel consumption figures in other units:
| L/100 km | km per litre | mpg (US) | mpg (imperial) |
| --- | --- | --- | --- |
| 4 | 25 | 58.8 | 70.62 |
| 5 | 20 | 47.04 | 56.5 |
| 6 | 16.67 | 39.2 | 47.08 |
| 7 | 14.29 | 33.6 | 40.35 |
| 8 | 12.5 | 29.4 | 35.31 |
| 9 | 11.11 | 26.13 | 31.39 |
| 10 | 10 | 23.52 | 28.25 |
| 12 | 8.333 | 19.6 | 23.54 |
| 15 | 6.667 | 15.68 | 18.83 |

Q: How do I convert L/100 km to km per litre?
A: 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.

Q: How do I convert km per litre to miles per gallon?
A: 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.

Q: Why are UK and US miles per gallon different?
A: 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.

Q: What is MPGe and how is it calculated?
A: 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.

Q: What does 0 km/L or 0 L/100 km mean?
A: 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.

Q: Is kWh per 100 km the same as Wh per km?
A: 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.

Q: Will I get the brochure figure?
A: 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: NIST Guide to the SI, Appendix B.9: mile per gallon (US) and the rule L/100 km = 235.215 divided by mpg; mile per hour, checked 2026-10-13 (https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9); NIST Guide to the SI, Appendix B.8: gallon (U.K. and Canadian imperial) = 4.546 09 litres, checked 2026-10-13 (https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8); Weights and Measures Act 1985, Schedule 1: the gallon is 4.54609 cubic decimetres, checked 2026-10-13 (https://www.legislation.gov.uk/ukpga/1985/72/schedule/1); NIST: the US gallon is 231 cubic inches (so 3.785411784 litres with the inch at exactly 2.54 cm), checked 2026-10-13 (https://www.nist.gov/how-do-you-measure-it/how-do-you-measure-fuel-gas-pump); 40 CFR 600.002: one gallon of gasoline is equivalent to 33.705 kilowatt-hours of electricity, checked 2026-10-13 (https://www.law.cornell.edu/cfr/text/40/600.002); fueleconomy.gov: how to read the electric vehicle label (MPGe and kWh per 100 miles), checked 2026-10-13 (https://www.fueleconomy.gov/feg/label/learn-more-electric-label.shtml); Daily FT, 18 December 2017: Around Sri Lanka on one tank (a Vito averaging 20.8 km per litre, quoted in km per litre), checked 2026-10-13 (https://www.ft.lk/Motor/Around-Sri-Lanka-on-one-tank-Mercedes-Benz-VITO-beats-the-odds/55-645419)

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