Fuel Economy Converter Formula
Understand the math behind the fuel economy converter. Each variable explained with a worked example.
Formulas Used
Liters per 100 km
l_per_100km = mpg > 0 ? 235.215 / mpg : 0Kilometers per Liter
km_per_liter = mpg * 0.425144Miles per Liter
miles_per_liter = mpg * 0.264172Variables
| Variable | Description | Default |
|---|---|---|
mpg | Miles per Gallon (MPG)(mpg) | 30 |
How It Works
Fuel Economy Conversion
L/100km = 235.215 / MPG
km/L = MPG × 0.4251
MPG is used in the US and UK. L/100km is the standard in most other countries. Lower L/100km = better fuel economy.
Worked Example
A car with 30 MPG fuel economy.
mpg = 30
- 01L/100km = 235.215 / 30 = 7.8 L/100km
- 02km/L = 30 × 0.4251 = 12.8 km/L
Frequently Asked Questions
What is considered good fuel economy?
In the US, 30+ MPG is good for a car (7.8 L/100km or less). Hybrids get 40-60 MPG (3.9-5.9 L/100km).
What is the difference between US and UK MPG?
UK (Imperial) gallons are larger. 1 UK gallon = 1.2 US gallons. So UK MPG numbers are higher for the same car.
Ready to run the numbers?
Open Fuel Economy Converter