Fuel Economy Calculator
This calculator computes fuel economy instantly: a car doing 12 km/L uses 8.33 L/100km.
- Convert between km/L, L/100km and MPG, then cost your trip per month and per year.
Figures are estimates from this calculator’s standard formula — adjust the inputs in the tool below for your exact number.
Fuel consumption conversion table
| L/100km | km/L | US MPG |
|---|---|---|
| 5 | 20 | 47 |
| 6 | 16.7 | 39.2 |
| 8 | 12.5 | 29.4 |
| 10 | 10 | 23.5 |
| 12 | 8.3 | 19.6 |
| 15 | 6.7 | 15.7 |
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How Fuel Economy Calculation Works
Fuel economy measures how efficiently your vehicle converts fuel into distance traveled. This calculator determines your real-world fuel efficiency by comparing distance covered to fuel consumed, helping you track vehicle performance and budget fuel costs.
- 1
Select Unit System
Choose Imperial (MPG) or Metric (km/L) measurements
- 2
Enter Fuel Used
Input the amount of fuel consumed in gallons or liters
- 3
Enter Distance
Input the distance traveled with that fuel
- 4
View Results
See fuel economy, cost per mile, and annual projections
Use Cases
Efficiency Tracking
Monitor your vehicle's fuel efficiency over time to detect changes
Vehicle Comparison
Compare fuel economy between different vehicles before purchasing
Cost Budgeting
Calculate annual fuel costs based on your actual efficiency
Maintenance Monitoring
Detect potential mechanical issues through declining fuel economy
Tips
- 1
Use the tank-to-tank method for accurate measurements - fill completely each time
- 2
Track fuel economy separately for city and highway driving
- 3
Compare your results to EPA ratings to assess vehicle performance
- 4
Seasonal variations are normal - cold weather reduces fuel economy
- 5
Sudden drops in economy may indicate maintenance needs
Common Mistakes
Using estimated amounts instead of actual fuel purchased
Not filling to the same level each time for consistent measurements
Comparing results from different driving conditions
Expecting to match EPA estimates in real-world driving
FAQs
How do I convert km/L to L/100km?
How much fuel does my car use per month?
What is the difference between US and UK MPG?
What is 10 L/100km in MPG?
How do I calculate trip fuel cost?
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