Fuel Economy Converter

About the Fuel Economy Converter

The free Fuel Economy Converter converts between Miles Per Gallon (MPG), Liters per 100 Kilometers (L/100km), and Kilometers per Liter (km/L). It supports both US and UK (Imperial) gallons so you can compare vehicles across different markets accurately.

Fuel economy ratings vary by country. The United States measures in MPG (US gallons), the United Kingdom uses MPG (Imperial gallons), and most of Europe and Canada report in L/100km. Japan and some Asian markets use km/L. These differences make cross-market vehicle comparisons confusing without a reliable converter.

Our converter uses the precise relationship: L/100km = 235.215 ÷ US MPG (or 282.481 ÷ UK MPG). Enter any value and review the equivalents in all three systems. Perfect for car buyers, travelers, and automotive enthusiasts.

When This Page Helps

Comparing vehicles from different markets requires consistent fuel economy units. This converter eliminates manual math and prevents errors from confusing US and Imperial gallons.

How to Use the Inputs

1. Select the fuel economy unit you are converting from.
2. Enter the fuel economy value.
3. View the converted values in all other supported units.
4. Toggle between US MPG and UK (Imperial) MPG if needed.
5. Use results to compare vehicles across markets.

Example Calculation

Tips & Best Practices

• Remember that UK (Imperial) MPG values are always higher than US MPG for the same car because Imperial gallons are larger.
• Lower L/100km means better fuel economy — the scale is inverted compared to MPG.
• A typical compact car gets 30–40 US MPG (7–8 L/100km), while an SUV might get 18–25 US MPG (9–13 L/100km).
• Hybrid vehicles often achieve 45–60 US MPG (4–5 L/100km).
• City vs highway MPG can differ by 20–40%, so always compare like-for-like.

Understanding Fuel Economy Standards

Fuel economy measurements evolved differently across regions. The US adopted miles per gallon during the 1975 CAFE standards. Europe standardized on L/100km because metric units were already prevalent and the inverse scale directly relates to consumption cost.

Why the Conversion Is Not Linear

Because MPG and L/100km have an inverse relationship, the conversion is not linear. Improving from 10 to 20 MPG saves far more fuel than improving from 30 to 40 MPG. The L/100km scale makes this more intuitive since each unit of improvement represents the same fuel saving.

Real-World vs. Rated Economy

Lab-tested fuel economy (EPA, WLTP, NEDC) differs from real-world driving. Factors like temperature, terrain, driving style, and tire pressure all affect actual consumption. Use converter results as a baseline comparison, not a guaranteed prediction.

Frequently Asked Questions

• How do I convert MPG to L/100km?

  Divide 235.215 by the MPG value (US gallons). For example, 25 MPG = 235.215 ÷ 25 = 9.41 L/100km. For UK MPG, divide 282.481 by the MPG value instead.

• What is the difference between US and UK MPG?

  US MPG uses the US gallon (3.785 liters), while UK MPG uses the Imperial gallon (4.546 liters). The same car will show a higher MPG number in UK units. Multiply US MPG by 1.201 to get UK MPG.

• Why does Europe use L/100km instead of MPG?

  L/100km directly tells you how much fuel you'll use for a given distance, making cost estimation straightforward. It's also metric, consistent with the rest of European measurements.

• What is km/L and where is it used?

  Kilometers per liter (km/L) is the metric equivalent of MPG. It's widely used in Japan, India, and parts of Southeast Asia. Higher km/L means better fuel economy.

• Is 7 L/100km good fuel economy?

  Yes, 7 L/100km (≈ 33.6 US MPG) is good for a mid-size gasoline sedan. Compact cars may achieve 5–6 L/100km, while full-size SUVs might use 10–14 L/100km.

• How do I calculate fuel cost per mile or kilometer?

  Divide the fuel price per gallon by your MPG to get cost per mile. For metric: multiply L/100km by the price per liter, then divide by 100 to get cost per kilometer.