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2025-06-25

Fuel Efficiency Calculator: Calculate MPG and L/100km

Calculate fuel efficiency (MPG or L/100km) based on distance and fuel consumed with this easy-to-use calculator.


Fuel Efficiency Calculator

Understanding your vehicle's fuel efficiency helps you make smarter decisions about driving habits, vehicle maintenance, and even your next car purchase. Whether you track MPG (miles per gallon) or L/100km (liters per 100 kilometers), knowing your actual fuel consumption is the first step to saving money and reducing your carbon footprint.

How Fuel Efficiency is Calculated

The formula is straightforward:

MPG = Distance (miles) ÷ Fuel (gallons)

L/100km = (Fuel (liters) ÷ Distance (km)) × 100

Note that higher MPG means better efficiency, while lower L/100km means better efficiency—they're inversely related.

Factors Affecting Fuel Efficiency

Driving Speed: Most vehicles achieve optimal efficiency between 50-60 mph. Speeding significantly reduces MPG.

Tire Pressure: Under-inflated tires increase rolling resistance and can reduce fuel efficiency by 3-5%.

Vehicle Maintenance: Regular oil changes, clean air filters, and proper wheel alignment all contribute to better fuel economy.

Driving Habits: Aggressive acceleration and braking waste fuel. Smooth, consistent driving is more efficient.

Weight: Extra weight in your vehicle reduces fuel efficiency. Remove unnecessary items from your trunk.

Tips to Improve Fuel Efficiency

  • Maintain steady speeds using cruise control on highways

  • Remove roof racks when not in use

  • Use the recommended fuel grade for your vehicle

  • Keep your engine properly tuned

  • Plan routes to avoid traffic congestion
  • Tracking your fuel efficiency over time reveals patterns and helps you identify when your vehicle needs maintenance or when your driving habits need adjustment.