Master Your Fuel Costs
With fluctuating energy prices in 2026, converting between fuel efficiency metrics is essential. Our enhanced converter helps you quickly convert between MPG, L/100km, and other efficiency units with instant results and visual feedback.
Planning a trip or comparing two cars? Use these related tools: Trip Cost Calculator, Fuel Cost Comparison Calculator, Fuel Cost Calculator, and Car TCO Calculator.
How to Calculate Trip Costs Manually
If you want to verify the numbers or calculate offline, the math is straightforward. You need three numbers: Distance, Efficiency, and Price.
Using MPG (US/UK)
Example: 200 miles ÷ 25 MPG = 8 Gallons.
8 Gallons × $3.50 = $28.00
Using L/100km (Metric)
Example: 300 km × 8 L/100km ÷ 100 = 24 Liters.
24 Liters × €1.60 = €38.40
US MPG vs. L/100km: The Core Calculation
The relationship between Miles Per Gallon (MPG) and Liters per 100 Kilometers (L/100km) is reciprocal, not linear. This means as one value goes up, the other goes down. This fundamental difference often confuses buyers comparing international models.
To Calculate L/100km
Example: 30 MPG → 235.215 / 30 = 7.84 L/100km
To Calculate MPG (US)
Example: 8 L/100km → 235.215 / 8 = 29.4 MPG
Global Fuel Standards in 2026
As we move through 2026, vehicle efficiency standards continue to evolve. The transition to WLTP (Worldwide Harmonized Light Vehicles Test Procedure) in Europe and updated EPA testing in the US means official figures are more realistic than in previous decades.
- MPG (US): Remains the standard in America. A "good" rating in 2026 is typically defined as above 30 MPG for SUVs and 40+ MPG for sedans.
- L/100km: The global metric. Lower is better. Sub-5.0 L/100km is now the benchmark for efficient hybrids.
- MPGe (Miles Per Gallon equivalent): The EPA standard for EVs. It represents the distance traveled on 33.7 kWh of energy. The 2026 Tesla Model 3 Long Range achieves over 130 MPGe.
- kWh/100km: The metric standard for EV consumption. Lower is better. Typical EVs use 15–20 kWh/100km.
The "UK Gallon" Trap
Critical Warning for Buyers
If you are reading a reviews from a British website (e.g., Top Gear, Carwow), the MPG figures are likely in Imperial (UK) MPG.
1 MPG (UK) ≈ 0.83 MPG (US)
A car rated at 50 MPG in the UK is only achieving about 41.6 MPG in US terms. Always verify the source of your data to avoid overestimating a vehicle's efficiency by ~20%.
Quick Reference: Efficiency Benchmarks
| Vehicle Class | Target MPG (US) | Target L/100km | Efficiency Rating |
|---|---|---|---|
| Hybrid Sedan | 50+ | < 4.7 | Excellent |
| Compact SUV | 30-35 | 7.8 - 6.7 | Good |
| Large SUV/Truck | 18-24 | 13.0 - 9.8 | Average |
| Performance Car | < 20 | > 11.8 | Poor |
Popular Fuel Consumption Conversions
Use this detailed chart to quickly convert between the most common fuel economy standards. We've included specific values often searched for, such as 39.2 MPG and 5.9 L/100km.
| MPG (US) | MPG (UK) | L/100km | km/L | Efficiency Note |
|---|---|---|---|---|
| 15 MPG | 18.0 MPG | 15.7 L/100km | 6.4 km/L | Low (Trucks/V8s) |
| 20 MPG | 24.0 MPG | 11.8 L/100km | 8.5 km/L | Below Average |
| 25 MPG | 30.0 MPG | 9.4 L/100km | 10.6 km/L | Average |
| 30 MPG | 36.0 MPG | 7.8 L/100km | 12.8 km/L | Good (SUV Benchmark) |
| 33 MPG | 39.6 MPG | 7.1 L/100km | 14.0 km/L | Good |
| 35 MPG | 42.0 MPG | 6.7 L/100km | 14.9 km/L | Very Good |
| 36 MPG | 43.2 MPG | 6.5 L/100km | 15.3 km/L | Very Good |
| 39.2 MPG | 47.1 MPG | 6.0 L/100km | 16.7 km/L | Excellent |
| 40 MPG | 48.0 MPG | 5.9 L/100km | 17.0 km/L | Gas Sedan Benchmark |
| 50 MPG | 60.0 MPG | 4.7 L/100km | 21.3 km/L | Hybrid Territory |
| 60 MPG | 72.1 MPG | 3.9 L/100km | 25.5 km/L | PHEV / Strong Hybrid |
| 65 MPG | 78.1 MPG | 3.6 L/100km | 27.6 km/L | Ultra Efficient |
Frequently Asked Questions
- How do I convert MPG to L/100km?
- To convert US MPG to L/100km, divide 235.215 by the MPG rating. For example, 30 MPG converts to 7.84 L/100km (235.215 ÷ 30). This formula accounts for the reciprocal nature of the units: MPG measures distance per volume, while L/100km measures volume per distance.
- How do I calculate fuel cost for a trip?
- Use the formula: (Distance ÷ MPG) × Fuel Price. For a 500-mile trip in a 30 MPG car with gas at $3.50/gal: (500 ÷ 30) × 3.50 = $58.33. Using metric: (Distance × L/100km ÷ 100) × Price/L. For 800km at 8L/100km and €1.80/L: (800 × 8 ÷ 100) × 1.80 = €115.20.
- What is considered good fuel economy in 2026?
- In 2026, 'good' fuel economy varies by class but expectations have risen. For non-hybrid compacts, aim for 40+ MPG (≤5.9 L/100km). Hybrids often exceed 50-60 MPG (≤4.7 L/100km). For SUVs, 30+ MPG (≤7.8 L/100km) is the new benchmark due to stricter EPA and WLTP standards.
- Why is UK MPG higher than US MPG?
- The UK Imperial gallon (4.546 L) is approximately 20% larger than the US liquid gallon (3.785 L). Therefore, a vehicle traveling 30 miles on a UK gallon is traveling further per unit of fuel than one on a US gallon. Always check the origin of the MPG figure; 30 MPG (US) equals about 36 MPG (UK).
- How can I save money on fuel?
- Drive smoothly (avoid rapid acceleration), keep tires properly inflated (under-inflation increases consumption), remove excess weight (roof racks, heavy cargo), and use cruise control on highways. For each 5 mph you drive over 50 mph, you pay an additional ~$0.25 per gallon in lost efficiency.
- What is MPGe and how does it relate to MPG?
- MPGe (Miles Per Gallon equivalent) is a metric used by the EPA to compare electric vehicles (EVs) with gas cars. It assumes 33.7 kWh of electricity contains the same energy as one gallon of gasoline. A rating of 100 MPGe indicates the EV is as efficient as a gas car getting 100 MPG.
- Why is L/100km arguably a better metric than MPG?
- L/100km is linear related to fuel consumption and cost. Saving 1 L/100km always saves the same amount of fuel over a fixed distance. MPG is non-linear: improving from 10 to 20 MPG saves far more fuel than improving from 40 to 50 MPG. This makes L/100km more intuitive for calculating actual savings.
- What affects my car's fuel efficiency the most?
- Driving habits (aggressive acceleration/braking can lower MPG by 15-30%), vehicle maintenance (under-inflated tires decrease efficiency by ~0.2% per 1 psi), and aerodynamics (roof racks increase drag significantly at highway speeds) are the primary factors you can control.
- Does using air conditioning reduce fuel economy?
- Yes, significantly. Using A/C can reduce fuel economy by 10-25% in very hot weather. However, at highway speeds, open windows create aerodynamic drag that may consume more fuel than the A/C. In 2026 modern climate control systems are more efficient, but the impact remains measurable.
- How do I convert kWh/100km to MPGe?
- Use the formula: MPGe = 2094.3 ÷ kWh/100km. For example, an EV consuming 15 kWh/100km is equivalent to approx. 140 MPGe (2094.3 ÷ 15). This helps compare EV efficiency directly with gas car MPG.
- What does 10 liters per 100 kilometers mean?
- It means your vehicle consumes 10 liters of fuel to travel a distance of 100 kilometers. In US terms, this equals roughly 23.5 MPG. Lower numbers (like 5.9 L/100km) represent better fuel economy, while higher numbers (like 11.8 L/100km) indicate higher fuel consumption.
- How do I convert 40 MPG to L/100km?
- 40 MPG (US) is equivalent to approximately 5.9 liters per 100 kilometers (5.88 L/100km to be precise). This is considered a very fuel-efficient rating for a non-hybrid petrol car.
- What is 30 MPG in L/100km?
- 30 MPG (US) converts to roughly 7.8 liters per 100 kilometers. This is a common target for modern SUVs and crossovers in mixed driving conditions.