Fuel Economy Dashboard
Compare efficiency across global standards instantly.
Quick Facts
- 01MPG measures how far you go on 1 unit of gas. Higher is better.
- 02L/100km measures how much gas is consumed over distance. Lower is better.
- 03UK Gallons (4.55L) are bigger than US Gallons (3.79L).
Explore More Unit Converters
Mastering Fuel Economy: The Complete Guide
In a global automotive market, understanding fuel efficiency figures can be a nightmare. You might see a car reviewed with 50 MPG in the UK, only to realize that equals 41 MPG in the US. Or you might travel to Europe and be perplexed by L/100km. Our Fuel Economy Converter is designed to cut through this confusion with a unified, instant dashboard.
Advanced Tool Features
Universal Units
Simultaneously convert MPG (US), MPG (UK), L/100km, and km/L. No need to switch modes or select dropdowns.
Efficiency Grade
Our unique "Speedometer" gauge visually rates the fuel economy from Red (Poor) to Green (Excellent).
Vehicle Presets
One-click buttons for common vehicles like "Hybrid", "Truck", or "Sedan" to instantly see benchmark numbers.
How to Use the Converter
- Enter a Value: Type a number into any of the four input boxes. For example, if you know your car gets 30 MPG (US), just type "30" in that box.
- Watch the Ripple Effect: All other fields updates instantly. You will see that 30 MPG (US) equals roughly 7.8 L/100km.
- Check the Gauge: Look at the top bar. Is your needle in the green zone? That means you have good efficiency.
- Save Your Result: Click "Save Result" to store the calculation in your local history list for reference.
Understanding the Units
Imperial (MPG)
Miles Per Gallon measures distance. It answers the question: "If I have one gallon of fuel, how far can I drive?"
- The "Bigger is Better" Rule: A higher MPG number means more efficient. You are traveling more miles for the same cost.
- US vs UK Trap: A US Gallon is ~3.79 liters. A UK Gallon is ~4.55 liters. Because the UK gallon is bigger, UK MPG numbers are always higher, even for the same car.
Metric (L/100km)
Liters per 100 Kilometers measures consumption. It answers the question: "To drive 100 kilometers, how much fuel must I buy?"
- The "Smaller is Better" Rule: A lower L/100km number refers to using less fuel. 5 L/100km is better than 10 L/100km.
- Direct Costing: This unit is loved by accountants and fleet managers because it makes calculating trip costs easier (Fuel Price × Liters Needed).
Conversion Formulas
| Conversion | Formula |
|---|---|
| MPG (US) → L/100km | 235.215 / MPG |
| L/100km → MPG (US) | 235.215 / L |
| MPG (US) → MPG (UK) | MPG × 1.201 |
| km/L → L/100km | 100 / km/L |
Real-World Applications
Importing Vehicles
If you are buying a JDM (Japanese Domestic Market) car, specs will be in km/L. If you are importing from the UK, they will be in Imperial MPG. Use this tool to convert specs to your local standard before buying.
International Road Trips
Driving from the US (Gallons) to Canada (Liters)? Or UK (Miles) to France (Kilometers)? Convert your efficiency to estimate fuel costs accurately in the currency and units of the country you are visiting.
Why Use This Calculator?
100% Private
No data is sent to servers. All math happens on your device.
Instant & Interactive
See results update in real-time. No clicking "Calculate" repeatedly.
Visual Feedback
The efficiency gauge helps you instantly spot "gas guzzlers".
History & Presets
Compare multiple vehicles easily using the built-in history log.
Frequently Asked Questions
Why are there two different MPG units (US and UK)?
The confusion stems from the definition of a 'gallon'. The US Gallon (3.785 liters) is smaller than the Imperial/UK Gallon (4.546 liters). Because the UK gallon holds more fuel, a car will travel further on one UK gallon than one US gallon, leading to a higher MPG figure for the exact same efficiency. 1 MPG (UK) ≈ 1.2 MPG (US).
How do I convert L/100km to MPG?
L/100km measures consumption (fuel used), while MPG measures distance (miles traveled). They are inversely related. To convert L/100km to US MPG, divide 235.215 by your L/100km value. For example, 8 L/100km became 235.215 / 8 ≈ 29.4 MPG.
Is a lower L/100km number better?
Yes! L/100km stands for 'Liters used per 100 kilometers'. A lower number means you burned less fuel to go the same distance. This is the opposite of MPG, where a higher number is better.
What is considered 'Good' fuel economy today?
For a modern combustion car, anything above 30 MPG (US) or below 7.8 L/100km is considered good. Hybrids often achieve 50+ MPG (US) or < 4.7 L/100km. Electric vehicle equivalents (MPGe) can be over 100 MPG.
How accurate is the 'Efficiency Gauge'?
The gauge on our dashboard uses general automotive standards. 'Red' indicates poor economy (<15 MPG), 'Yellow/Orange' is average for older or heavy vehicles (15-25 MPG), 'Light Green' is good for modern sedans (25-40 MPG), and 'Bright Green' indicates excellent hybrid-level efficiency (40+ MPG).
Can I convert electric vehicle (EV) efficiency?
Yes, indirectly. EVs use MPGe (Miles Per Gallon equivalent). You can enter the MPGe rating (like 130 for a Tesla Model 3) to see what that would look like in terms of L/100km or UK MPG, though L/100km is strictly for liquid fuel volume.
Does this tool work offline?
Yes! Once loaded, the Fuel Economy Converter runs entirely in your browser using JavaScript. You can use it without an internet connection, making it perfect for road trips in remote areas.
What is km/L used for?
Kilometers per Liter (km/L) is common in parts of Asia, Latin America, and the Middle East. It is the metric equivalent of MPG—measuring distance per unit of fuel. To convert km/L to L/100km, simply divide 100 by the km/L value.