Conversion Tools

Fuel Economy Converter

Convert between MPG, L/100km, km/L, and calculate fuel costs

Fuel Economy Input

Enter a value and select the unit to convert

Select your input measurement unit

MPG

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Fuel Cost Calculator
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Quick Scenarios

Trip & Annual Fuel Calculator

Calculate fuel needed and costs for trips

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Visualizations

Fuel economy comparisons and cost projections

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Conversion Reference Table

Common fuel economy values in all units

Reference

Formulas, definitions, and conversion factors

Core Conversion Formulas
L/100km = 235.215 ÷ MPG (US)
Lower L/100km = better efficiency. Higher MPG = better efficiency.
Unit Definitions

Understanding the different measurement systems.

  • MPG (US): Miles per US gallon (3.785 L)
  • MPG (UK): Miles per Imperial gallon (4.546 L)
  • L/100km: Liters per 100 kilometers
  • km/L: Kilometers per liter
Conversion Constants

Key factors used in conversions.

  • 1 US gallon = 3.78541 liters
  • 1 UK gallon = 4.54609 liters
  • 1 mile = 1.60934 km
  • UK MPG ≈ US MPG × 1.201
Efficiency Guidelines

General fuel economy categories.

  • Excellent: 40+ MPG / <6 L/100km
  • Good: 30-40 MPG / 6-8 L/100km
  • Average: 20-30 MPG / 8-12 L/100km
  • Poor: <20 MPG / >12 L/100km
All Conversion Formulas
From MPG (US):
• L/100km = 235.215 ÷ MPG
• km/L = MPG × 0.425144
• MPG (UK) = MPG (US) × 1.20095

From L/100km:
• MPG (US) = 235.215 ÷ L/100km
• km/L = 100 ÷ L/100km
• MPG (UK) = 282.481 ÷ L/100km

From km/L:
• L/100km = 100 ÷ km/L
• MPG (US) = km/L × 2.35215
• MPG (UK) = km/L × 2.82481

Understanding Fuel Economy

Why Different Units?

Different regions use different measurement systems based on historical standards.

  • US: Miles per gallon (MPG)
  • UK: Imperial MPG (larger gallon)
  • Europe/Asia: L/100km or km/L
  • Canada: Often uses both systems
L/100km vs MPG

These units measure fuel economy inversely.

  • MPG: Higher is better (more miles per gallon)
  • L/100km: Lower is better (less fuel used)
  • The relationship is hyperbolic, not linear
  • Small MPG changes matter more at low MPG
Fuel Cost Factors

Actual fuel costs depend on many variables.

  • Regional fuel prices vary significantly
  • Driving conditions affect real-world economy
  • City vs highway driving differences
  • Vehicle load and conditions