MPG to L/100km Converter

About the MPG to L/100km Converter

Converting between MPG (miles per gallon) and L/100km (liters per 100 kilometers) is essential when comparing vehicles across markets. The US and UK use MPG while most of the world uses L/100km. Because the conversion is an inverse relationship, it's not as simple as multiplying by a single factor.

This converter handles both directions. Enter an MPG value to see L/100km, or enter L/100km to see MPG. It also shows the UK imperial MPG equivalent, since UK gallons are larger than US gallons.

Whether you're shopping for an imported vehicle, reading international car reviews, or traveling abroad and comparing fuel costs, this converter makes it easier to switch between fuel economy systems.

When This Page Helps

Vehicle specifications and reviews often use different fuel economy units depending on the market. This converter bridges the gap between US MPG and the metric L/100km standard, making it easy to compare vehicles from different countries or understand international fuel economy ratings.

How to Use the Inputs

1. Enter a value in the MPG field to convert to L/100km.
2. Or enter a value in the L/100km field to convert to MPG.
3. View both US MPG and UK Imperial MPG equivalents.
4. Use the results to compare vehicles across different markets.
5. Bookmark this page for quick reference when reading car reviews.

Example Calculation

Tips & Best Practices

• Remember: higher MPG = lower L/100km = better fuel economy.
• US gallons (3.785 L) are smaller than UK imperial gallons (4.546 L).
• A vehicle at 25 MPG (US) is about 9.4 L/100km.
• The conversion is not linear — a 5 MPG improvement at 15 MPG saves more fuel than at 35 MPG.
• EPA combined ratings blend 55% city and 45% highway driving.
• Real-world MPG is typically 10–20% worse than EPA estimates.

Why Two Different Systems Exist

The US adopted MPG as its standard because fuel was historically cheap and plentiful — drivers cared about how far they could go. Europe and other regions adopted L/100km because it directly relates to fuel cost and consumption, which is more practical for budgeting.

The MPG Illusion

One important concept is the MPG illusion. Because MPG is a ratio with fuel in the denominator, improvements at the low end save far more fuel than improvements at the high end. Going from 10 to 15 MPG saves more fuel than going from 35 to 100 MPG over the same distance. L/100km avoids this problem entirely.

Common Conversion Reference Points

15 MPG = 15.7 L/100km (large truck). 20 MPG = 11.8 L/100km (SUV). 25 MPG = 9.4 L/100km (midsize). 30 MPG = 7.8 L/100km (compact). 40 MPG = 5.9 L/100km (hybrid). 50 MPG = 4.7 L/100km (plug-in hybrid).

When You Need This Conversion

Use this converter when reading international car reviews, comparing imported vehicles, traveling abroad, or discussing fuel economy with people in other countries. It's also useful when checking manufacturer specs that may be listed in a different unit than what you're familiar with.

Frequently Asked Questions

• Why is the conversion not a simple multiplication?

  MPG and L/100km have an inverse (reciprocal) relationship. MPG measures distance per unit of fuel, while L/100km measures fuel per unit of distance. The conversion formula is 235.215 ÷ value, which produces a hyperbolic curve, not a straight line.

• What is the difference between US MPG and UK MPG?

  US gallons are 3.785 liters, while UK imperial gallons are 4.546 liters. This means UK MPG figures are about 20% higher than US MPG for the same vehicle. Always check which gallon is being used when reading specifications.

• What does 10 L/100km equal in MPG?

  10 L/100km = 235.215 ÷ 10 = 23.5 MPG (US). This is typical for a larger SUV or truck. In UK imperial MPG, that's about 28.2 MPG.

• What does 40 MPG equal in L/100km?

  40 MPG (US) = 235.215 ÷ 40 = 5.88 L/100km. This is very efficient, typical of a hybrid or small diesel car. In UK terms, that's about 48 MPG.

• Why does improving from 15 to 20 MPG save more fuel than 35 to 40 MPG?

  This is the MPG illusion. At 15 MPG, you use 6.67 gallons per 100 miles. At 20 MPG, you use 5.0 gallons — saving 1.67 gallons. At 35 MPG, you use 2.86 gallons; at 40 MPG, 2.50 gallons — saving only 0.36 gallons. L/100km avoids this illusion.

• How do I convert km/L to L/100km?

  Divide 100 by the km/L value. For example, 14 km/L = 100 ÷ 14 = 7.14 L/100km. To then get MPG, divide 235.215 by the L/100km result.