Fuel Economy Calculator
Calculate fuel economy: L/100km, km/L, MPG (US). Distance and fuel used inputs.
Free · Runs in your browser · No signup
Examples to try
Economy
km/L = distance ÷ fuel. L/100km = fuel ÷ distance × 100.
Common mistakes
- Mixing miles with liters without converting.
- Using tank capacity instead of fuel actually used.
- Comparing city and highway tanks as if identical.
Scope: Trip fuel math helper for personal tracking.
How to Use
Enter your values in the fields above and click Calculate to get instant results. All computations run locally in your browser. No data is ever uploaded or stored.
Related Calculators
Fuel Economy in Two Systems
Different regions measure fuel economy differently. L/100 km measures consumption per distance (lower is better — used in Europe, Canada, Australia). km/L and MPG measure distance per fuel unit (higher is better — used in Japan, US, UK).
L/100km = (liters used / distance km) × 100
km/L = distance km / liters used
MPG (US) ≈ km/L × 2.352
Fuel Economy Benchmarks
Hybrid sedan: 4.0–5.0 L/100km · Compact car: 6.0–7.5 L/100km
Midsize sedan: 7.0–9.0 L/100km · Full-size SUV: 10–14 L/100km
Pickup truck: 11–16 L/100km
Improve economy: keep tires inflated, remove excess weight, drive smoothly, and maintain clean air filters. Regular maintenance alone can improve efficiency 4–10%.
Fuel Economy Calculation
CalcSolver's fuel economy calculator computes efficiency in both km/L and L/100km from distance traveled and fuel consumed. The L/100km standard (used in most countries) measures consumption per distance, while km/L (used in Japan and some others) measures distance per fuel unit. In the United States, MPG (miles per gallon) is the standard metric. Understanding these different units helps you compare vehicles across international markets and make informed purchasing decisions.
L/100km vs MPG: Understanding the Difference
L/100km and MPG measure fuel economy inversely. With L/100km, a lower number is better — it means less fuel is needed to travel 100 kilometers. With MPG, a higher number is better — it means more miles are covered per gallon. To convert between them: L/100km = 235.215 / MPG and MPG = 235.215 / L/100km. For example, a car rated at 30 MPG consumes about 7.84 L/100km, while a car at 6 L/100km achieves roughly 39.2 MPG. This inverse relationship often confuses buyers comparing international vehicle specifications.
Fuel Cost Estimation
Knowing your fuel economy lets you estimate travel costs. The formula is simple: Cost = (Distance / Efficiency) × Price per Unit. If your car averages 8 L/100km and fuel costs $1.50 per liter, a 600km trip costs (600 / 100) × 8 × $1.50 = $72. For a road trip covering 2,000km at 7 L/100km with fuel at $1.40/L, budget approximately $196. Tracking fuel costs over time reveals seasonal price fluctuations and helps identify the cheapest refueling stations along your regular routes.
Real-World Examples
City vs Highway Driving: A compact sedan might achieve 6.5 L/100km on the highway but 9.2 L/100km in city traffic due to frequent stops and idling. The 40% difference highlights why mixed driving ratings fall between these figures.
Hybrid Advantage: A Toyota Prius averages about 4.2 L/100km (56 MPG), while a comparable non-hybrid sedan averages 7.5 L/100km (31 MPG). Over 15,000km annually, the hybrid saves roughly 495 liters — about $740 at $1.50/L.
Electric Vehicle Comparison: EVs use kWh/100km instead of L/100km. A Tesla Model 3 consumes about 15 kWh/100km. At $0.12/kWh, that equals $1.80 per 100km — far cheaper than any gasoline vehicle.
Driving Efficiency Tips
- Maintain steady speeds: Most vehicles are most efficient between 60-80 km/h. Every 10 km/h above 80 increases fuel consumption by roughly 10%.
- Check tire pressure monthly: Under-inflated tires increase rolling resistance, reducing fuel economy by up to 3%.
- Reduce idling: An idling engine consumes 0.5-1.5 liters per hour. Turn off the engine if stopped for more than 60 seconds.
- Remove excess weight: Every 50kg of extra weight increases fuel consumption by about 1-2%.
- Use cruise control: On flat highways, cruise control maintains optimal engine load and prevents speed fluctuations that waste fuel.
- Plan routes efficiently: Combine errands into single trips, avoid peak traffic hours, and use navigation apps to find the most fuel-efficient routes.
Road Trip Fuel Planning
For long-distance travel, calculate your total fuel needs before departure. Divide total distance by your car's efficiency (in km/L) to find liters needed, then multiply by expected fuel price. For a 1,500km round trip at 10 km/L and $1.50/L: (1,500 / 10) × $1.50 = $225. Add a 10% buffer for detours and city driving. When planning multi-day trips, research fuel prices along your route — prices can vary by 20-30% between regions and countries. Consider fuel tank capacity as well: a 50-liter tank at 8 L/100km gives a maximum range of 625km, so plan refueling stops accordingly to avoid running low in remote areas.
Tips and Best Practices
- Track your fuel economy over time: Record distance and fuel at each fill-up to spot trends. Declining efficiency may signal maintenance issues before they become costly repairs.
- Compare vehicles fairly: When shopping for a new car, compare L/100km or MPG ratings for the same driving cycle (city, highway, or combined). Mixed ratings give the most realistic daily-use estimate.
- Account for seasonal variations: Cold weather reduces fuel economy by 15-25% due to increased engine friction, longer warm-up times, and use of heating systems. Summer driving with air conditioning adds 5-10% consumption.
- Use fuel price apps: Combine your fuel economy knowledge with real-time fuel price apps to find the cheapest stations along your route. Savings of $0.10-0.20 per liter add up significantly over long trips.
- Consider total cost of ownership: A fuel-efficient vehicle may cost more upfront but save thousands over its lifetime. Calculate the break-even point by comparing purchase price difference against annual fuel savings.
Use CalcSolver's unit converter for distance and volume conversions, and the percentage calculator for fuel budget adjustments.
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Frequently Asked Questions
How do I calculate fuel economy?
Divide the distance traveled by the fuel used. For MPG: miles ÷ gallons. For L/100km: (liters ÷ kilometers) × 100. Lower L/100km means better economy; higher MPG means better economy.
What is the difference between MPG and L/100km?
MPG (miles per gallon) measures distance per unit of fuel — higher is better. L/100km (liters per 100 kilometers) measures fuel per unit of distance — lower is better. They are inversely related.
How can I improve my fuel economy?
Drive at steady speeds, maintain proper tire pressure, reduce idling, remove excess weight, use cruise control on highways, and keep up with regular maintenance like air filter and spark plug replacement.
How do I calculate the fuel cost for a road trip?
Divide your total distance by your car's fuel efficiency (in km/L) to get liters needed, then multiply by the fuel price per liter. For example: 800km trip at 12 km/L with fuel at $1.50/L = (800/12) × $1.50 = $100. Add a 10-15% buffer for detours and city driving.
Are hybrid and electric vehicles worth the fuel savings?
Hybrids typically use 30-50% less fuel than equivalent gasoline cars. A hybrid saving 3 liters per 100km over 15,000km/year saves 450 liters (about $675 at $1.50/L). Electric vehicles are even cheaper to fuel — roughly $1.50-$2.50 per 100km versus $10-$15 for gasoline vehicles.
Why is my real-world fuel economy worse than the manufacturer rating?
Manufacturer ratings are derived from controlled laboratory tests using standardized driving cycles. Real-world driving includes traffic, hills, air conditioning, cold starts, aggressive driving, and higher speeds — all of which reduce fuel economy. Expect 10-20% worse economy in daily driving compared to official ratings.