Fuel consumption conversion lets you compare car stickers and trip computers when one country lists miles per gallon and another lists liters per 100 kilometers. MPG rises when efficiency improves; L/100 km falls — so the math is reciprocal, not a single multiply. This guide covers US and UK gallons, L/100 km, and km/L with charts and driving examples.
Convert fuel economy now: Open the free Fuel Consumption Converter — MPG, L/100 km, km/L, and related rates.
What fuel consumption conversion is
Fuel economy (or consumption) describes how much fuel a vehicle uses for distance traveled. The US and UK often quote miles per gallon (different gallon sizes). Much of the world quotes liters per 100 kilometers. Some markets also use kilometers per liter. Converting between them lets you compare a European brochure to a US window sticker without guessing.
Plain-language fuel formulas
- mpg US → L/100 km: L/100 km ≈ 235.215 ÷ mpg US.
- L/100 km → mpg US: mpg US ≈ 235.215 ÷ L/100 km.
- mpg UK → L/100 km: L/100 km ≈ 282.481 ÷ mpg UK (imperial gallon is larger).
- L/100 km → km/L: km/L = 100 ÷ L/100 km.
- km/L → L/100 km: L/100 km = 100 ÷ km/L.
Always confirm US vs UK gallon before converting MPG — the factors differ.
Fuel consumption tables
MPG (US) to L/100 km
| mpg US | L/100 km (approx.) |
|---|---|
| 20 | 11.8 |
| 25 | 9.4 |
| 30 | 7.8 |
| 35 | 6.7 |
| 40 | 5.9 |
| 50 | 4.7 |
L/100 km to km/L
| L/100 km | km/L |
|---|---|
| 5 | 20.0 |
| 6 | 16.7 |
| 8 | 12.5 |
| 10 | 10.0 |
| 12 | 8.3 |
Worked examples
Example 1 — US sticker to metric brochure
A car rates 32 mpg US. In L/100 km: 235.215 ÷ 32 ≈ 7.35 L/100 km.
Example 2 — European rating to US mpg
A listing shows 6.2 L/100 km. In mpg US: 235.215 ÷ 6.2 ≈ 37.9 mpg US.
Example 3 — trip computer in km/L
Your display averages 14.5 km/L. In L/100 km: 100 ÷ 14.5 ≈ 6.90 L/100 km.
Common fuel consumption mistakes
- Using the US mpg factor on a UK mpg figure (or the reverse).
- Treating higher L/100 km as “better” — lower L/100 km is more efficient.
- Comparing city and highway cycles as if they were the same test.
- Converting volume units (gallons↔liters) alone without the distance half of the rate.
Fuel consumption converter tools
Use the Fuel Consumption Converter for MPG, L/100 km, and km/L pairs.
Related reading
- Unit conversion chart & calculator guide — full category map