Fuel Economy Calculator
Calculate your vehicle's fuel economy by entering distance driven and fuel used. Get results in km/L, L/100km, and MPG (US and UK) with an efficiency rating. The fuel economy calculator helps you track real-world fuel efficiency, compare vehicles, monitor driving habits, and identify when your car's consumption is abnormal.
Enter Values
Total distance since last fill-up
Litres or gallons consumed
Result
Enter values above and click Calculate to see your result.
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Formula
How it works: Divide the total distance you drove by the total fuel consumed to find your kilometres per litre. Convert to L/100km by dividing 100 by your km/L result. Convert to US MPG by multiplying km/L by 2.352.
Worked Example
How to Measure Your Vehicle's Fuel Economy
Fuel economy is the distance your vehicle travels per unit of fuel. Tracking it over time helps you spot maintenance issues, evaluate driving habits, and compare vehicles objectively.
- Fill your tank completely, reset your trip meter, drive normally, then fill up again. Divide the km driven by the litres added to get your real-world km/L
- Excellent fuel economy is 5 L/100km or less (20+ km/L), typical of hybrids and efficient small cars. Average is 8-10 L/100km (10-12.5 km/L) for medium sedans and crossovers
- Highway driving at 90-100 km/h typically gives 15-25% better fuel economy than city driving with frequent stops and starts
- A sudden drop in fuel economy (15-20% worse than usual) often signals a maintenance issue: dirty air filter, worn spark plugs, faulty oxygen sensor, or under-inflated tyres
- Under-inflated tyres alone can reduce fuel economy by 3-5%. Check tyre pressure monthly against the manufacturer's recommended PSI on the door placard
Track your fuel economy every fill-up. Use this calculator alongside our Fuel Cost per KM Calculator to convert efficiency into actual dollar costs per trip.
You can also calculate changes using our Fuel Cost per KM Calculator, Fuel Consumption Converter, Trip Fuel Cost Calculator or Petrol vs Diesel Cost Calculator.
Fuel Economy Benchmarks by Vehicle Type
Typical real-world fuel economy ranges for different vehicle categories. Compare your result to these benchmarks to see where your vehicle stands.
| Vehicle Type | km/L | L/100km | MPG (US) | Rating |
|---|---|---|---|---|
| Hybrid (Toyota Prius, etc.) | 20-25 | 4.0-5.0 | 47-59 | Excellent |
| Small hatchback | 15-20 | 5.0-6.7 | 35-47 | Very Good |
| Medium sedan | 12-15 | 6.7-8.3 | 28-35 | Good |
| Compact SUV/Crossover | 10-13 | 7.7-10.0 | 24-31 | Average |
| Large sedan | 9-12 | 8.3-11.1 | 21-28 | Average |
| Large SUV | 7-10 | 10.0-14.3 | 16-24 | Below Average |
| Pickup truck/Ute | 6-9 | 11.1-16.7 | 14-21 | Below Average |
| Performance/Sports car | 7-11 | 9.1-14.3 | 16-26 | Varies |
| Diesel (medium) | 16-22 | 4.5-6.3 | 38-52 | Very Good |
Note: Real-world fuel economy is typically 10-20% worse than manufacturer-stated figures due to differences in test conditions. City driving can be 20-30% worse than highway. Air conditioning adds 5-10% to consumption. Figures shown are combined city/highway estimates. For educational reference only.
Frequently Asked Questions
How do I calculate my car's fuel economy?
Fill your tank completely and note the odometer reading (or reset your trip meter). Drive normally until you need to refuel. Fill up again and note the litres added and distance driven. Divide km by litres: 450 km / 38 litres = 11.8 km/L. For L/100km, divide 100 by your km/L: 100 / 11.8 = 8.5 L/100km. Repeat over 3 to 4 fill-ups for a reliable average.
What is good fuel economy in km per litre?
Excellent is 20+ km/L (hybrids and efficient diesels). Very good is 15-20 km/L (small hatchbacks). Good is 12-15 km/L (medium sedans). Average is 9-12 km/L (SUVs and crossovers). Below average is 6-9 km/L (large SUVs and trucks). If your car is getting significantly worse than its rated economy, it may need a service.
What is a normal L/100km for a car?
For a typical medium sedan, 7 to 9 L/100km is normal. Small cars achieve 5 to 7 L/100km. SUVs and crossovers use 8 to 12 L/100km. Anything above 12 L/100km for a standard car suggests either a large vehicle, aggressive driving style, or a maintenance issue. Diesel vehicles typically achieve 15-25% better L/100km than equivalent petrol models.
How do I convert km/L to MPG?
Multiply km/L by 2.352 for US MPG, or by 2.825 for UK (Imperial) MPG. For example, 12 km/L = 28.2 US MPG = 33.9 UK MPG. To convert L/100km to US MPG, divide 235.21 by the L/100km value: 235.21 / 8.5 = 27.7 MPG.
Why is my fuel economy worse than the manufacturer states?
Manufacturer figures are tested under controlled lab conditions (WLTP or EPA cycles). Real-world driving typically gives 10-20% worse results due to: city driving with frequent stops, air conditioning use, higher speeds, cold weather, roof racks, under-inflated tyres, carrying heavy loads, and aggressive acceleration. Track your economy over several fill-ups to establish your real baseline.
What causes a sudden drop in fuel economy?
A sudden 15-20% increase in fuel consumption often indicates: a dirty or clogged air filter (easy fix), worn or fouled spark plugs, a faulty oxygen sensor, stuck brake caliper (dragging), under-inflated tyres, or a failing fuel injector. If your economy drops noticeably between fill-ups, have the vehicle inspected. Even something as simple as a stuck thermostat or low coolant can affect fuel economy.
AI Assistant
Ask about this calculator
I can help you understand the fuel economy calculator formula, interpret your results, and answer follow-up questions.
Try asking
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