How to convert fuel consumption
There are two kinds of fuel economy unit. Distance per fuel (km/L, mpg) is higher for an efficient vehicle. Fuel per distance (L/100 km) is lower for an efficient vehicle. Converting between the two kinds means dividing a constant by the value, not multiplying:
- km/L to L/100 km: L/100 km = 100 ÷ km/L (20 km/L = 5 L/100 km).
- US mpg to L/100 km: L/100 km = 235.215 ÷ mpg.
- UK mpg to L/100 km: L/100 km = 282.481 ÷ mpg.
- US mpg to km/L: multiply by 0.425144.
Indian manufacturers quote km/L (ARAI figures); Europe uses L/100 km; the US and UK use mpg, but with different gallons. Trip fuel cost = distance ÷ km/L × fuel price per litre.
Fuel consumption conversions
Each of these has its own page with the formula, worked examples and a full conversion table:
All fuel consumption units on this converter
| Unit | Symbol | 1 unit equals | System |
|---|---|---|---|
| Kilometre per litre | km/L | 1 km/L | Distance per fuel |
| Mile per US gallon | mpg (US) | 0.4251437074 km/L | Distance per fuel |
| Mile per UK gallon | mpg (UK) | 0.3540061899 km/L | Distance per fuel |
| Mile per litre | mi/L | 1.609344 km/L | Distance per fuel |
| Litre per 100 km | L/100 km | see formula above | Fuel per distance |
| Litre per km | L/km | see formula above | Fuel per distance |
| US gallon per 100 miles | gal/100 mi (US) | see formula above | Fuel per distance |
Frequently asked questions
How do I convert km/L to L/100 km?
Divide 100 by the km/L figure. A car that gives 16 km/L uses 100 ÷ 16 = 6.25 L per 100 km.
Why are US and UK mpg different?
A UK (imperial) gallon is 4.546 L and a US gallon is 3.785 L, so the same car shows about 20% more mpg in UK units.
What is good fuel economy for a car in India?
Small petrol hatchbacks typically get 18–24 km/L (ARAI), compact SUVs 14–18 km/L and diesel cars 18–25 km/L. Real-world figures are usually 10–20% lower.