Fuel Consumption Converter
Convert fuel consumption and efficiency units — MPG, L/100km, km/L, and more. Free online fuel economy converter for cars, trucks, and fleet management.
Understanding Fuel Consumption
Fuel consumption measures how much fuel a vehicle uses to travel a given distance. Lower consumption means better efficiency and lower operating costs. Different regions express fuel consumption differently: North America uses miles per gallon (MPG), Europe uses liters per 100 kilometers (L/100km), and some countries use kilometers per liter (km/L).
MPG and km/L are distance-per-fuel metrics where higher numbers indicate better efficiency. L/100km is a fuel-per-distance metric where lower numbers indicate better efficiency. Understanding these conventions helps when comparing vehicles from different markets.
Fuel Consumption Formulas
Calculate fuel consumption from distance and fuel used:
MPG = Distance (miles) / Fuel Used (gallons)
L/100km = (Fuel Used (L) / Distance (km)) × 100
km/L = Distance (km) / Fuel Used (L)
Example: A car travels 600 km using 48 liters of fuel:
L/100km = (48 / 600) × 100 = 8.0 L/100km
km/L = 600 / 48 = 12.5 km/L
MPG (US) = 235.215 / 8.0 = 29.4 MPG
MPG to L/100km Conversion
Convert between MPG (US) and L/100km using these formulas:
L/100km = 235.215 / MPG (US)
MPG (US) = 235.215 / L/100km
For UK (imperial) gallons:
L/100km = 282.481 / MPG (UK)
MPG (UK) = 282.481 / L/100km
Quick reference conversions:
| MPG (US) | L/100km | km/L | MPG (UK) |
|---|---|---|---|
| 10 | 23.52 | 4.25 | 12.01 |
| 15 | 15.68 | 6.38 | 18.01 |
| 20 | 11.76 | 8.50 | 24.02 |
| 25 | 9.41 | 10.63 | 30.02 |
| 30 | 7.84 | 12.75 | 36.03 |
| 35 | 6.72 | 14.88 | 42.03 |
| 40 | 5.88 | 17.00 | 48.04 |
| 50 | 4.70 | 21.25 | 60.05 |
| 60 | 3.92 | 25.50 | 72.06 |
| 80 | 2.94 | 34.00 | 96.08 |
Fuel Cost Calculator
Calculate fuel costs from consumption and fuel price:
Cost per km = (Price per L) / (km/L)
Cost per 100km = (L/100km) × (Price per L)
Annual Cost = Annual Distance × Cost per km
Example: Fuel costs $1.45/L, vehicle uses 7.5 L/100km, annual driving is 18,000 km:
Cost per 100km = 7.5 × $1.45 = $10.88
Cost per km = $10.88 / 100 = $0.109
Annual Cost = 18,000 × $0.109 = $1,962
Comparing to a more efficient vehicle using 5.5 L/100km:
Annual savings = 18,000 × (7.5 - 5.5) / 100 × $1.45 = $522
EPA Fuel Economy Ratings
The US Environmental Protection Agency tests vehicles and publishes fuel economy ratings:
| Vehicle Class | City MPG | Highway MPG | Combined MPG |
|---|---|---|---|
| Subcompact (2024 avg) | 28 to 33 | 36 to 43 | 31 to 37 |
| Compact (2024 avg) | 26 to 31 | 34 to 40 | 29 to 35 |
| Mid-size (2024 avg) | 23 to 28 | 31 to 37 | 26 to 32 |
| Compact SUV (2024 avg) | 24 to 29 | 30 to 35 | 26 to 32 |
| Mid-size SUV (2024 avg) | 20 to 24 | 26 to 30 | 22 to 27 |
| Full-size SUV (2024 avg) | 15 to 19 | 20 to 25 | 17 to 21 |
| Pickup Truck (2024 avg) | 16 to 21 | 20 to 26 | 18 to 23 |
| Hybrid Compact (2024 avg) | 45 to 55 | 45 to 53 | 45 to 54 |
| Electric (MPGe, 2024 avg) | 110 to 140 | 95 to 120 | 100 to 130 |
CO2 Emissions from Fuel
Estimate carbon dioxide emissions from fuel consumption:
CO2 (g/km) = (L/100km) × 23.1
Gasoline produces approximately 2,310 g CO2 per liter
CO2 (g/km) = (L/100km) × 26.8
Diesel produces approximately 2,680 g CO2 per liter
Example: A gasoline vehicle using 8 L/100km:
CO2 = 8 × 23.1 = 184.8 g/km
Annual CO2 emissions for 15,000 km driving:
Annual CO2 = 15,000 × 184.8 / 1000 = 2,772 kg = 2.77 tonnes
Factors Affecting Fuel Consumption
- Driving behavior: Aggressive acceleration and braking can increase consumption by 15 to 30 percent
- Speed: Fuel economy typically peaks at 50 to 60 mph and drops above 70 mph
- Vehicle weight: Every 100 kg reduces fuel economy by about 1 to 2 percent
- Tire pressure: Under-inflated tires increase consumption by 0.2 percent per psi below recommended
- Aerodynamics: Roof racks and open windows increase drag and consumption
- Engine maintenance: Dirty filters and old spark plugs reduce efficiency
- Air conditioning: AC use can increase consumption by 5 to 25 percent in city driving
- Traffic conditions: Stop-and-go traffic consumes more fuel than steady highway driving
Tips for Better Fuel Economy
- Drive smoothly with gradual acceleration and braking
- Maintain steady speeds using cruise control on highways
- Keep tires properly inflated to recommended pressure
- Remove unnecessary weight from the vehicle
- Use air conditioning sparingly in city driving
- Combine errands to reduce total distance traveled
- Follow recommended maintenance schedules
- Use the recommended grade of motor oil
- Plan routes to avoid traffic congestion
- Consider a fuel-efficient or hybrid vehicle for your next purchase
Frequently Asked Questions
Why is highway MPG higher than city MPG?
Highway driving involves steady speeds with minimal braking, allowing the engine to operate at optimal efficiency. City driving requires frequent stops and accelerations, which consume extra fuel. Idling at traffic lights also wastes fuel. Most vehicles achieve 20 to 30 percent better fuel economy on highways than in cities.
Does premium fuel improve MPG?
Premium fuel only benefits engines designed for it. Using premium in a regular-fuel vehicle provides no measurable improvement in fuel economy or performance. Using regular in a premium-required vehicle can cause engine knock and reduced performance. Follow the manufacturer recommendation in your owner manual.
How accurate is the trip computer MPG display?
Vehicle trip computers typically show optimistic readings, overestimating MPG by 5 to 15 percent. For accurate measurements, fill the tank completely, reset the trip odometer, drive normally, then divide miles driven by gallons needed to refill. Track several tanks for a reliable average.
What is a good MPG for a car?
Good MPG depends on vehicle type. Subcompact cars should achieve 30 to 40 MPG combined. Mid-size sedans typically get 25 to 35 MPG. Compact SUVs achieve 25 to 32 MPG. Hybrid vehicles can exceed 45 to 55 MPG. Electric vehicles are rated in MPGe (miles per gallon equivalent), typically 100 to 130 MPGe.
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