Fuel Economy Converter
Convert between MPG, L/100km, and km/L.
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1 mpg = 235.215 L/100km
| Miles per Gallon (US) (mpg) | L/100km (L/100km) |
|---|---|
| 1 | 235.215 |
| 2 | 117.6075 |
| 5 | 47.043 |
| 10 | 23.5215 |
| 15 | 15.681 |
| 20 | 11.76075 |
| 25 | 9.4086 |
| 50 | 4.7043 |
| 75 | 3.1362 |
| 100 | 2.35215 |
| 150 | 1.5681 |
| 200 | 1.176075 |
| 250 | 0.94086 |
| 500 | 0.47043 |
| 1,000 | 0.235215 |
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Understanding Fuel Economy Units
The US uses miles per gallon (mpg) — higher is better. Most other countries use liters per 100 kilometers (L/100km) — lower is better. These two metrics are inversely related:
mpg = 235.214 ÷ (L/100km)
For example, a car rated at 30 mpg uses about 7.84 L/100km.
Fuel Economy Reference
| Vehicle Type | MPG | L/100km |
|---|---|---|
| Average US car | ~25 | ~9.4 |
| Hybrid | ~50 | ~4.7 |
| SUV | ~20 | ~11.8 |
| EV equivalent | 100+ MPGe | N/A |
Fuel economy drops significantly at highway speeds above 55 mph. Each 5 mph increase over 50 mph is roughly equivalent to paying an additional $0.15–$0.30 per gallon for gas, according to the US Department of Energy. Aggressive driving (rapid acceleration and braking) can reduce fuel economy by 15–30% at highway speeds.
When to use this
You are comparing a car reviewed in Europe (rated at 6.5 L/100km) with one reviewed in the US (rated at 35 MPG) and want to know which actually uses less fuel. Or you are planning a road trip in a rental car abroad and the fuel economy is displayed in a unit you do not use daily. Fuel economy conversion is essential for international car shopping, travel planning, and understanding automotive reviews from other countries.
The US uses miles per gallon (MPG), most of Europe and Australia use liters per 100 kilometers (L/100km), and some countries like Japan and India use kilometers per liter (km/L). The tricky part is that MPG and km/L are "bigger is better" units (more distance per unit of fuel), while L/100km is "smaller is better" (less fuel per unit of distance). The conversion between them is not linear — it involves an inverse relationship, making mental math unreliable.
Good to know
The conversion is not a simple multiplication. Because MPG measures distance-per-fuel and L/100km measures fuel-per-distance, you cannot just multiply by a fixed factor. The formula is L/100km = 235.215 / MPG (US). So 30 MPG = 7.84 L/100km, and 40 MPG = 5.88 L/100km. The relationship is inverse — improvements at low MPG save more fuel than the same MPG improvement at high MPG.
US MPG and UK MPG are different. Because the US gallon (3.785 L) is smaller than the imperial gallon (4.546 L), a car rated at 40 MPG in the UK would be about 33 MPG by US measurement. Always check which gallon standard is being used when reading specifications.
The "MPG illusion" is real and important. Improving from 10 to 20 MPG saves more fuel than improving from 30 to 60 MPG over the same distance. This is because fuel consumption has a diminishing-returns relationship with MPG. L/100km is actually a more intuitive unit for comparing fuel costs because it scales linearly with fuel consumed.
Quick Reference
| MPG (US) | L/100km | km/L | Vehicle Type |
|---|---|---|---|
| 15 MPG | 15.68 | 6.38 | Large truck/SUV |
| 20 MPG | 11.76 | 8.50 | Full-size sedan |
| 25 MPG | 9.41 | 10.63 | Midsize car |
| 30 MPG | 7.84 | 12.75 | Compact car |
| 35 MPG | 6.72 | 14.88 | Efficient sedan |
| 40 MPG | 5.88 | 17.00 | Hybrid |
| 50 MPG | 4.70 | 21.25 | Plug-in hybrid |
| 60 MPG | 3.92 | 25.50 | Efficient hybrid |