Fuel Economy Converter
Convert between MPG, L/100km, and other fuel economy units with precision.
Popular Fuel Economy Unit Conversions
MPG (US) ↔ MPG (UK)
• 30 MPG (US) = 36.03 MPG (UK)
• 25 MPG (US) = 30.02 MPG (UK)
• 20 MPG (US) = 24.02 MPG (UK)
MPG ↔ L/100km
• 30 MPG = 7.84 L/100km
• 25 MPG = 9.41 L/100km
• 20 MPG = 11.76 L/100km
km/L ↔ MPG (US)
• 12 km/L = 28.22 MPG
• 10 km/L = 23.52 MPG
• 8 km/L = 18.82 MPG
Complete Fuel Economy Conversion Guide
Understanding Fuel Economy Measurement Systems
Fuel economy measurement varies globally between two primary approaches: distance per volume (miles per gallon, kilometers per liter) and volume per distance (liters per 100 kilometers, gallons per 100 miles). Each system has advantages for different applications and regional preferences.
The Two Measurement Approaches
Distance per Volume:
Higher numbers = better efficiency (MPG, km/L)
Volume per Distance:
Lower numbers = better efficiency (L/100km, gal/100mi)
Understanding this fundamental difference is crucial for accurate fuel economy comparisons and calculations.
Essential Conversion Factors & Relationships
Core Conversion Formulas
MPG (US) to L/100km: L/100km = 235.214 ÷ MPG
L/100km to MPG (US): MPG = 235.214 ÷ L/100km
MPG (US) to MPG (UK): MPG (UK) = MPG (US) × 1.201
km/L to MPG (US): MPG = km/L × 2.352
Key Fuel Economy Benchmarks
Regional Standards
US Standard
Miles per Gallon
(US gallon = 3.785 L)
UK Standard
Miles per Gallon
(Imperial gallon = 4.546 L)
European Standard
Liters per 100 km
(Lower = better)
International Metric
Kilometers per Liter
(Higher = better)
Professional Applications
Fleet Management & Transportation
- • Vehicle selection and procurement decisions
- • Route optimization and fuel cost analysis
- • Driver performance monitoring and training
- • Maintenance scheduling based on efficiency trends
- • Carbon footprint tracking and environmental reporting
Automotive Industry
- • Vehicle design and engineering optimization
- • EPA fuel economy ratings and compliance
- • Marketing specifications and consumer information
- • Competitive analysis and benchmarking
- • Research and development performance targets
Environmental & Regulatory
- • Corporate Average Fuel Economy (CAFE) standards
- • Carbon emissions calculations and reporting
- • Environmental impact assessments
- • Sustainability metrics and goal tracking
- • Government fleet efficiency requirements
Consumer Decision Making
- • Vehicle purchase comparisons and cost analysis
- • Annual fuel cost estimations
- • Trip planning and budget calculations
- • Hybrid and electric vehicle evaluations
- • Insurance and tax incentive qualifications
Logistics & Supply Chain
- • Delivery route optimization
- • Carrier selection and performance evaluation
- • Transportation cost modeling
- • Supply chain carbon footprint analysis
- • Fuel procurement and hedging strategies
Understanding Different Fuel Economy Units
Miles per Gallon (US) [MPG]
The standard US measurement using US gallons (3.785 liters). Higher numbers indicate better fuel efficiency. Used for EPA ratings and consumer vehicle specifications.
Miles per Gallon (UK) [MPG]
Based on Imperial gallons (4.546 liters), resulting in approximately 20% higher values than US MPG. Important for UK vehicle specifications and international comparisons.
Liters per 100 Kilometers [L/100km]
European standard where lower numbers indicate better efficiency. Preferred for scientific analysis and international automotive specifications.
Kilometers per Liter [km/L]
Metric equivalent to MPG, commonly used in Asia and international markets. Higher numbers indicate better efficiency.
Real-World Fuel Economy Factors
Vehicle Type Benchmarks
Driving Conditions Impact
City Driving:
Typically 20-30% lower efficiency
Highway Driving:
Optimal efficiency at 45-65 mph
Combined Driving:
EPA standard 55% city, 45% highway
Stop-and-go Traffic:
Can reduce efficiency by 40%
Weather Conditions:
Cold weather reduces efficiency 10-20%
Efficiency Improvement Strategies
Proper Tire Inflation
2-3% improvement potential
Regular Maintenance
5-10% improvement potential
Smooth Driving
10-20% improvement potential
Speed Management
7-14% at 55-65 mph vs 75+ mph
Route Optimization
5-15% improvement potential
Environmental Impact Calculations
Carbon Emissions Relationships
Gasoline:
19.6 lbs CO₂ per gallon
Diesel:
22.4 lbs CO₂ per gallon
Carbon Footprint Calculation:
Annual miles ÷ MPG × emission factor
Efficiency improvements directly reduce emissions
Fuel Cost Analysis
Annual Fuel Cost Formula:
(Annual miles ÷ MPG) × Price per gallon
• Comparative cost analysis between vehicles
• Fuel price volatility impact on total cost of ownership
• Break-even analysis for fuel-efficient vehicle purchases
Frequently Asked Questions
Why do US and UK MPG differ?
The difference stems from gallon size: US gallons contain 3.785 liters while Imperial gallons contain 4.546 liters. This makes UK MPG approximately 20% higher than US MPG for the same vehicle.
Which measurement system is most accurate?
All systems are equally accurate when properly applied. L/100km is preferred for scientific analysis, while MPG is more intuitive for consumers. The key is consistency in measurement methodology.
How accurate are EPA fuel economy ratings?
EPA ratings provide standardized comparisons but may differ from real-world results by 10-20% depending on driving conditions, vehicle maintenance, and individual driving habits.
What causes fuel economy to vary seasonally?
Cold weather reduces efficiency through increased engine warm-up time, denser air, winter fuel blends, heating system use, and reduced tire pressure. Summer can also see reduced efficiency due to air conditioning use.
How do I improve my vehicle's fuel economy?
Key strategies include maintaining proper tire pressure, regular vehicle maintenance, smooth acceleration and braking, optimal speed management (45-65 mph), route planning, and reducing unnecessary weight and aerodynamic drag.