How to Use This Tool
Enter a Value
Type the fuel efficiency value you want to convert into the input field. Decimals are fully supported.
Choose Your Units
Pick a From unit and a To unit from the dropdowns. Use the swap button to flip them instantly.
Read the Result
The converted value appears instantly below the inputs. Click Copy to put it on your clipboard.
See All Conversions
Scroll down to see the same fuel efficiency expressed in every other supported unit at once.
Frequently Asked Questions
Is this tool really free?
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Yes, completely free with no limits and no sign-up. Everything runs in your browser with no server costs.
Is my data sent to a server?
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No. All conversion math happens directly in your browser. Nothing you type is ever sent anywhere.
What units are supported?
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5 units: Miles per US Gallon (MPG US), Miles per Imperial Gallon (MPG UK), Kilometers per Liter (km/L), Liters per 100 Kilometers (L/100km), and Kilometers per US Gallon (km/gal).
What is the difference between US and Imperial MPG?
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A US gallon is about 3.785 liters while an Imperial gallon is about 4.546 liters. So the same car gets a higher MPG number in Imperial gallons. For example, 30 MPG US is about 36 MPG Imperial.
What is L/100km?
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Liters per 100 kilometers measures how many liters of fuel a car uses to travel 100 km. Lower is better. It is the standard fuel economy unit in Europe, Australia, and much of the world.
How is L/100km different from km/L?
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They are inversely related. A car that does 10 km/L uses 10 L/100km. A car that does 20 km/L uses only 5 L/100km. The tool handles this inverse relationship automatically.
How do I convert MPG to L/100km?
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Set From to Miles per US Gallon and To to Liters per 100 km. For example, 30 MPG US is about 7.84 L/100km.
How accurate are the conversions?
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The tool uses standard conversion factors and displays up to 10 significant figures. Results are accurate for comparing car specifications and planning fuel costs.
Can I see all conversions at once?
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Yes. Below the main result, the tool shows the same value in every other unit in a scrollable list.
Why do some countries use L/100km instead of MPG?
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L/100km directly tells you how much fuel you will use for a given distance, making it easier to calculate fuel costs. MPG tells you how far you can go on a given amount of fuel. Both are useful, just framed differently.
What Is Fuel Efficiency Converter?
Fuel Efficiency Converter is a free tool that converts between 5 fuel economy units right in your browser. It handles the tricky inverse relationship between "distance per fuel" units (MPG, km/L) and "fuel per distance" units (L/100km) automatically, so you always get the right answer. Nothing you type is ever sent anywhere - all math runs locally on your device.
Whether you are comparing car specs from different countries, estimating fuel costs for a road trip, or understanding an imported vehicle's economy rating, the result updates live as you type and shows every unit at once.
Features Explained
5 Fuel Economy Units
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Convert between Miles per US Gallon, Miles per Imperial Gallon, Kilometers per Liter, Liters per 100 Kilometers, and Kilometers per US Gallon.
US and Imperial MPG
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Both US and Imperial gallon-based MPG are included because a US gallon is about 20% smaller than an Imperial gallon. The same car gives different MPG numbers depending on which gallon you use.
L/100km for Europe and Beyond
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Liters per 100 km is the standard unit in Europe, Australia, Canada, and much of the world. Lower numbers mean better fuel economy.
Inverse Conversion Handled
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MPG and km/L measure distance per fuel (higher is better), while L/100km measures fuel per distance (lower is better). The tool handles this inverse relationship automatically.
Instant Conversion
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The result updates live as you type. There is no Convert button to click - you see the answer the moment your input changes.
All Conversions at Once
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Below the main result, a scrollable table shows the same fuel efficiency in every other unit simultaneously.
Swap Button
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Click the swap button between the From and To dropdowns to flip them instantly. The result recalculates right away.
Copy to Clipboard
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Click Copy to put the converted value on your clipboard instantly, ready to paste into a document or message.
High Precision
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Results are displayed with up to 10 significant figures, accurate enough for car specifications and fuel cost calculations.
100% Browser-Based
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All conversion math runs directly in your browser. Nothing you type is ever sent to any server - complete privacy.
Who Is This Tool For?
Car Buyers
Compare fuel economy ratings between cars sold in different countries that use different units like MPG, L/100km, or km/L.
Road Trippers
Estimate fuel costs for a trip by converting your car's economy between the units used at your origin and destination.
Expats and Immigrants
Understand fuel economy ratings in your new country's unit system after moving from a country that uses a different one.
Car Reviewers
Convert manufacturer-quoted fuel economy figures between US MPG, Imperial MPG, and L/100km for your audience.
Fleet Managers
Compare fuel efficiency across vehicles from different regions that report economy in different units.
Truck Drivers
Convert fuel economy ratings between MPG and L/100km when driving across borders or comparing rigs from different manufacturers.
Rental Car Customers
Understand the fuel economy of a rental car when it is listed in a unit you are not familiar with.
Automotive Engineers
Convert fuel efficiency test results between international standards that use different measurement units.
Environmental Researchers
Convert fuel consumption data between units when comparing emissions and efficiency across countries.
Students
Convert between fuel economy units for physics, environmental science, and engineering homework.
Teachers
Demonstrate the relationship between MPG and L/100km in real time during lessons about energy and transportation.
Motorcycle Riders
Convert motorcycle fuel economy between MPG, km/L, and L/100km when comparing bikes from different markets.
Boat Owners
Convert marine fuel consumption between gallons per hour and liters per hour equivalents for trip planning.
Journalists
Convert fuel economy figures in automotive reviews so readers in different countries understand the numbers.
Used Car Shoppers
Convert the fuel economy listed on an imported vehicle's spec sheet to the unit you are familiar with.
Fuel Cost Calculators
Convert fuel economy to L/100km to directly calculate how much fuel a trip will cost at local fuel prices.
Driving Instructors
Explain fuel economy differences between metric and imperial systems to students learning to drive.
Government Workers
Convert fuel efficiency data between national standards when preparing cross-border reports and regulations.
RV Owners
Convert motorhome fuel economy between MPG and L/100km when planning long trips or comparing RV models.
Hybrid and EV Researchers
Convert equivalent fuel economy ratings between MPGe and L/100km for comparison with conventional vehicles.
Insurance Agents
Understand fuel efficiency ratings in different units when assessing vehicle operating costs for clients.
Delivery Companies
Compare delivery van fuel economy across different manufacturers and markets that quote in different units.
Travel Bloggers
Include accurate fuel economy conversions in road trip articles so international readers understand the figures.
Anyone
Quickly convert any fuel efficiency value for any reason - car shopping, trip planning, curiosity, or comparison.
Tips for Best Results
US vs Imperial MPG
A US gallon is 3.785 liters; an Imperial gallon is 4.546 liters. The same car gets about 20% more MPG in Imperial than US gallons. Always check which one is being quoted.
MPG to L/100km quick estimate
Divide 235 by the US MPG value for a rough L/100km estimate. For example, 30 MPG is about 235/30 = 7.8 L/100km.
L/100km to MPG quick estimate
Divide 235 by the L/100km value. For example, 8 L/100km is about 235/8 = 29.4 MPG US.
Lower L/100km is better
L/100km measures fuel used, so a lower number means better efficiency. This is the opposite of MPG and km/L where higher is better.
Use the All Conversions table
Scroll below the main result to see the same fuel efficiency in every other unit at once. Great for comparing specs from different countries.
Use the swap button
Click the swap button between the dropdowns to flip From and To instantly.
Copy the result in one click
Click Copy next to the result to put the value on your clipboard.
Common fuel economies
A typical sedan gets about 30 MPG US (7.8 L/100km). A hybrid might get 50+ MPG US (4.7 L/100km). A truck might get 15-20 MPG US (12-16 L/100km).
Decimals are fully supported
You can type values like 7.5, 32.4, or 12.8. The tool handles decimal precision up to 10 significant figures.
Privacy is built in
Nothing you type is ever sent to any server. All math runs in your browser, so your data stays completely private.
Privacy & Security
This tool runs 100% in your browser. Your files stay entirely on your own device. Nothing is uploaded, nothing is shared, and no server, advertiser, or third party has access to your files.
If a tool saves your work on your own device, you can remove it at any time using the Clear All button. Some tools rely on an external service to return their result; in those cases, only the minimum data required for the request is sent, and never your files or content. Any ads shown on this page run in an isolated frame and cannot read, touch, or transmit anything you upload, paste, type, or download here. Advertisers may see standard visit information like your IP address and which page you're on, as described in our Privacy Policy, but your data itself stays fully under your control.
