Fuel Economy Calculator & Converter
Master your vehicle's efficiency. Convert effortlessly between MPG, L/100km, and km/L, and discover how simple driving adjustments can save you hundreds in fuel costs annually.
Calculate Fuel Economy
Convert Fuel Economy Units
Results
Enter distance and fuel consumed to calculate fuel economy
Fuel Economy Scale
Common Fuel Economy Values
Fuel Economy Conversion Factors
MPG to L/100km
235.215 / MPG = L/100km
L/100km to MPG
235.215 / L/100km = MPG
MPG to km/L
MPG × 0.425144 = km/L
Fuel Economy Explained: The Real Cost of Driving
Fuel economy is more than just a number on a sticker; it's a direct measure of your vehicle's financial and environmental impact. At its core, it tells you how much energy (fuel) is required to move your vehicle a specific distance.
While often overlooked, tracking your fuel economy is the first step to "Hypermiling"—the art of driving efficiently. A drop in your usual MPG average can also be an early warning sign of mechanical issues, such as low tire pressure, a clogged air filter, or failing spark plugs.
The Global Divide: MPG vs L/100km
If you travel internationally or browse car forums, you'll encounter a confusing divide in how efficiency is measured. It essentially boils down to two different philosophies:
- Efficiency MPG (Miles Per Gallon) and km/L measure distance. The question is: "If I have 1 unit of fuel, how far can I go?" Here, Higher is Better. This is standard in the US, UK, Canada, and parts of Asia.
- Consumption L/100km measures consumption. The question is: "To travel 100km, how much fuel do I need to buy?" Here, Lower is Better. This is the standard in Europe and most prominent in scientific analysis because it scales linearly with cost.
Real-World Expectations
| Vehicle Type | Typical MPG (US) | Typical L/100km |
|---|---|---|
| Heavy Duty Truck | 12 - 15 MPG | 15.7 - 19.6 L/100km |
| Mid-Size SUV | 20 - 26 MPG | 9.0 - 11.8 L/100km |
| Compact Sedan | 30 - 40 MPG | 5.9 - 7.8 L/100km |
| Hybrid Vehicle | 45 - 60 MPG | 3.9 - 5.2 L/100km |
How to Master Your MPG
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The "Egg" Technique
Imagine there is a raw egg between your foot and the gas pedal. Press gently enough not to break it. Smooth acceleration is the #1 way to save fuel.
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Highway Aerodynamics
Above 50mph, wind resistance costs more fuel than AC. Keep windows up on the highway and use AC; keep windows down in the city to save AC power.
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The Sweet Spot
Most cars are most efficient between 45-60 mph. Efficiency drops drastically above 70 mph due to air resistance.
Frequent Questions
Does using AC really ruin my MPG?
Yes, but it depends on speed. The AC compressor puts a load on the engine, reducing fuel economy by 10-20% in city driving. However, at highway speeds, the drag from open windows is worse than the AC load.
Is highway driving always more efficient?
Generally, yes. Constant speeds with minimal braking allow the engine to operate in its most efficient power band. Stop-and-go city traffic wastes energy through heat in the brakes and repeated acceleration.
How accurate are dashboard MPG displays?
They are "optimistic" estimates. Most onboard computers estimate fuel flow based on injector pulse width and can be off by 5-10%. Manual calculation at the pump is always the most accurate method.