How to convert 18 mpg to L/100 km
Liters per 100 km is the inverse of miles per gallon, so you divide a constant by the mpg value:
L/100 km = 235.215 ÷ 18 = 13.07
The constant 235.215 comes from 100 km ÷ 1.609344 km per mile × 3.785411 liters per US gallon.
What 18 mpg means in practice
| Fuel per 100 miles | 5.56 gallons |
| Fuel per 100 km | 13.07 liters |
| Fuel for 12,000 miles a year | 667 gallons |
| Fuel cost for 12,000 miles at $3.20/gal | $2,133 |
| CO₂ per mile (gasoline) | 494 g |
CO₂ is based on the EPA figure of 8,887 grams of CO₂ per gallon of gasoline. For your own trip costs, use the fuel cost calculator.
Is 18 mpg good?
This is low fuel economy, typical of large pickup trucks, full-size SUVs, vans and older V8 cars.
Values around 18 mpg
| US mpg | L/100 km | UK mpg | km/L |
|---|---|---|---|
| 14 mpg | 16.80 L/100 km | 16.8 UK mpg | 5.95 km/L |
| 15 mpg | 15.68 L/100 km | 18.0 UK mpg | 6.38 km/L |
| 16 mpg | 14.70 L/100 km | 19.2 UK mpg | 6.80 km/L |
| 17 mpg | 13.84 L/100 km | 20.4 UK mpg | 7.23 km/L |
| 18 mpg | 13.07 L/100 km | 21.6 UK mpg | 7.65 km/L |
| 19 mpg | 12.38 L/100 km | 22.8 UK mpg | 8.08 km/L |
| 20 mpg | 11.76 L/100 km | 24.0 UK mpg | 8.50 km/L |
| 21 mpg | 11.20 L/100 km | 25.2 UK mpg | 8.93 km/L |
| 22 mpg | 10.69 L/100 km | 26.4 UK mpg | 9.35 km/L |
Frequently asked questions
What is 18 mpg in L/100 km?
18 US mpg equals 13.07 L/100 km (235.215 ÷ 18).
What is 18 mpg in km/L?
18 US mpg equals 7.65 kilometers per liter.
Is 18 mpg good?
This is low fuel economy, typical of large pickup trucks, full-size SUVs, vans and older V8 cars.
What is 18 US mpg in UK mpg?
18 US mpg equals 21.6 imperial (UK) mpg.
Last updated November 10, 2026