A fuel consumption converter translates between MPG (US gallons), MPG (Imperial gallons), L/100km, and km/L — the four fuel economy standards used around the world. Note that US and Imperial MPG are not the same: a UK gallon is 20% larger than a US gallon.
Fuel Economy Converter
Fuel Cost Calculator
Fuel Economy Reference
| Vehicle Type | MPG US | MPG UK | L/100km | km/L |
|---|---|---|---|---|
| Hybrid (Toyota Prius) | 50 | 60.1 | 4.7 | 21.3 |
| Efficient sedan | 35 | 42.0 | 6.7 | 14.9 |
| Average new car (US) | 28 | 33.6 | 8.4 | 11.9 |
| SUV / crossover | 20 | 24.0 | 11.8 | 8.5 |
| Full-size truck / van | 15 | 18.0 | 15.7 | 6.4 |
How to Convert Fuel Consumption Units
Fuel consumption conversion is important when comparing vehicles from different countries or when your car displays one unit and you need another. The key formulas: MPG US = 235.215 / (L/100km) and L/100km = 235.215 / MPG US.
Step 1: US MPG vs Imperial MPG
Always clarify which gallon is being used. A US gallon is 3.785 liters; an Imperial (UK) gallon is 4.546 liters — 20% larger. So the same car gets higher Imperial MPG than US MPG. Example: 28 US MPG = 33.6 Imperial MPG for exactly the same car. When comparing US and UK cars, always convert to L/100km for a fair comparison.
Step 2: L/100km is an Inverse Relationship
Unlike MPG where higher is better, L/100km is lower-is-better. A car using 5 L/100km is more efficient than one using 10 L/100km. To convert: 235.215 / MPG US = L/100km. So 47 MPG US ≈ 5 L/100km, and 10 MPG US = 23.5 L/100km.
Step 3: Calculate Real-World Fuel Costs
Use the cost calculator above to estimate trip costs. For context: at $3.50/gallon US, a 300-mile trip costs $35 in a 30 MPG car but $70 in a 15 MPG truck. Over 15,000 miles/year, the difference between 25 MPG and 35 MPG is about $300/year at $3.50/gallon.
Frequently Asked Questions
How do I convert MPG to L/100km?
To convert US MPG to L/100km, divide 235.215 by the MPG value. Example: 30 MPG US = 235.215/30 = 7.84 L/100km. For Imperial MPG (UK), use 282.481/MPG. Note: US and Imperial gallons are different sizes (1 US gal = 3.785 L, 1 Imperial gal = 4.546 L), so 30 US MPG ≠ 30 Imperial MPG.
What is km/L and where is it used?
Kilometers per liter (km/L) is the fuel efficiency unit used in many Asian countries including Japan, Thailand, India, and South Korea. It is the direct inverse of L/100km — a higher number means better fuel economy. To convert km/L to L/100km, divide 100 by the km/L value.
What is the difference between US MPG and Imperial MPG?
US gallons and Imperial (UK) gallons are different sizes. 1 US gallon = 3.785 liters, while 1 Imperial gallon = 4.546 liters. A car rated at 30 US MPG would be rated at approximately 36 Imperial MPG — 20% higher for the same car. Always specify which MPG system when comparing vehicles across regions.
How do I calculate my fuel cost per mile?
Divide your fuel price per gallon by your MPG. Example: $3.50/gallon ÷ 30 MPG = $0.117 per mile. For metric: (fuel price per liter × L/100km) / 100 = cost per km. A 25 MPG car at $3.50/gallon costs $0.14/mile or about $28 per 200-mile trip.
Is this fuel consumption converter free?
Yes, completely free with no signup required. All conversions run instantly in your browser.