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About this tool
Convert fuel economy between km/l, l/100 km, US mpg and imperial mpg, with the fuel a given trip would use.
The Fuel Economy Unit Converter moves a fuel economy figure between kilometres per litre, litres per 100 km, miles per US gallon and miles per imperial gallon. Distance-per-volume and volume-per-distance units are reciprocals of each other, so l/100 km = 100 ÷ km/l, while the mpg figures scale by the gallon in use: 3.785411784 litres for the US gallon and 4.54609 litres for the imperial one. Enter one number and a trip distance to see every equivalent plus the litres and gallons the journey would take.
Open Fuel Economy Unit Converter on AltFTool — it loads instantly in your browser.
Type your 'Fuel economy figure' and pick its unit under 'Given in' - km/l, l/100 km, mpg US or mpg UK.
Add a 'Trip distance (km)' to see the litres, US gallons and imperial gallons that journey would burn at that economy.
Read every equivalent - kilometres per litre, litres per 100 km, miles per US gallon, miles per imperial gallon and miles per litre - and press 'Copy result'.
US and imperial mpg shown separately, so a 40 mpg UK car is not mistaken for a 40 mpg US one.
Handles the direction flip between km/l and l/100 km that trips up quick mental conversions.
Turns the economy into the actual litres and gallons a given distance consumes.
Divide 100 by the km/l figure: 15 km/l is 100 ÷ 15 = 6.67 l/100 km. The relationship is a reciprocal, not a scaling, so improvements at the efficient end matter less than they look — going from 20 to 25 km/l saves 1 litre per 100 km, while going from 5 to 6 km/l saves 3.3.
12.75 km/l if that is 30 miles per US gallon, or 10.62 km/l if it is 30 miles per imperial gallon. The conversion factors are 1 km/l = 2.352 US mpg and 1 km/l = 2.825 imperial mpg.
Because the imperial gallon is 4.54609 litres against the US gallon's 3.785411784 — about 20% larger — so the same car travels about 20% further on one. A car rated 40 mpg in the UK is roughly 33 mpg in the US, and the two figures are never directly comparable.
Higher is better for km/l and mpg because they measure distance covered per unit of fuel; lower is better for l/100 km because it measures fuel burned per fixed distance. Europe uses l/100 km partly because it scales linearly with fuel cost, which distance-per-volume units do not.
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