Instantly Convert MPG ↔ km/L ↔ L/100km — All Directions
Convert fuel economy per gallon to per litre (MPG to km/L), or switch between US gallon and Imperial gallon values. Includes L/100km, formula, reference table for popular cars, and real-world fuel saving tips — free, no sign-up needed.
Fuel economy is measured differently around the world — the US uses miles per gallon (mpg), the UK uses mpg with Imperial gallons, and most other countries use kilometres per litre (km/L) or litres per 100 km (L/100km). This converter handles all formats instantly and accurately.
Miles per gallon (mpg) measures how many miles a vehicle can travel on one gallon of fuel. A higher mpg means better fuel efficiency. The US gallon = 3.78541 litres, while the Imperial gallon (UK) = 4.54609 litres — making Imperial mpg figures roughly 20% higher than US mpg for the same vehicle. The US EPA rates new cars in mpg for city and highway driving.
Kilometres per litre (km/L) is the metric equivalent of mpg, widely used across Asia, Latin America, and parts of Africa. Like mpg, a higher km/L number means better fuel efficiency. 1 US mpg = 0.425144 km/L and 1 Imperial mpg = 0.354006 km/L. Japan officially uses km/L as its standard fuel economy rating unit for all new vehicles.
Litres per 100 kilometres (L/100km) is the standard fuel consumption unit in Europe, Australia, Canada, and China. Unlike mpg and km/L, a lower L/100km means better efficiency. The relationship is inverse: L/100km = 100 ÷ km/L, and US mpg = 235.215 ÷ L/100km. A typical modern car uses 6–8 L/100km in mixed driving conditions.
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The conversion between MPG and km/L uses the exact relationship between miles, kilometres, and the two gallon sizes. Since 1959, 1 mile = 1.609344 km exactly. The US gallon is defined as 231 cubic inches = 3.785411784 litres, and the Imperial gallon = 4.54609 litres. All formulas below are derived from these exact definitions.
The table below covers the most common MPG values — both US and Imperial — converted to km/L and L/100km. All values use the exact factors: 1 US mpg = 0.425144 km/L and 1 Imperial mpg = 0.354006 km/L.
| MPG (US) | km/L | L/100km | MPG (Imperial) | Typical Vehicle |
|---|---|---|---|---|
| 10 mpg | 4.25 km/L | 23.5 L/100km | 12.0 mpg | Large truck / heavy SUV |
| 15 mpg | 6.38 km/L | 15.7 L/100km | 18.0 mpg | Full-size pickup, V8 SUV |
| 20 mpg | 8.50 km/L | 11.8 L/100km | 24.0 mpg | Mid-size SUV, minivan |
| 25 mpg | 10.63 km/L | 9.41 L/100km | 30.0 mpg | Mid-size sedan (average) |
| 30 mpg | 12.75 km/L | 7.84 L/100km | 36.1 mpg | Compact car, Toyota Corolla |
| 35 mpg | 14.88 km/L | 6.72 L/100km | 42.1 mpg | Economy compact, Honda Civic |
| 40 mpg | 17.01 km/L | 5.88 L/100km | 48.1 mpg | Efficient compact / mild hybrid |
| 45 mpg | 19.13 km/L | 5.23 L/100km | 54.1 mpg | Hybrid sedan (Toyota Prius) |
| 50 mpg | 21.26 km/L | 4.70 L/100km | 60.1 mpg | Toyota Prius / Honda Insight |
| 55 mpg | 23.38 km/L | 4.28 L/100km | 66.1 mpg | Honda Civic Hybrid (2026) |
| 60 mpg | 25.51 km/L | 3.92 L/100km | 72.1 mpg | Plug-in hybrid (blended) |
The table below converts litres per 100 km — the standard fuel unit in Europe, Australia, and Canada — back to US and Imperial MPG. Remember: a lower L/100km = better fuel economy, opposite to MPG where higher is better.
| L/100km | MPG (US) | MPG (Imperial) | km/L | Typical Vehicle Type |
|---|---|---|---|---|
| 4.0 L/100km | 58.8 mpg | 70.6 mpg | 25.0 km/L | Best-in-class hybrid |
| 5.0 L/100km | 47.0 mpg | 56.5 mpg | 20.0 km/L | Excellent hybrid / EV range extender |
| 6.0 L/100km | 39.2 mpg | 47.1 mpg | 16.7 km/L | Efficient small car |
| 7.0 L/100km | 33.6 mpg | 40.4 mpg | 14.3 km/L | Average compact car |
| 8.0 L/100km | 29.4 mpg | 35.3 mpg | 12.5 km/L | Mid-size sedan, family car |
| 9.0 L/100km | 26.1 mpg | 31.4 mpg | 11.1 km/L | Large sedan / small SUV |
| 10.0 L/100km | 23.5 mpg | 28.2 mpg | 10.0 km/L | Mid-size SUV / crossover |
| 12.0 L/100km | 19.6 mpg | 23.5 mpg | 8.3 km/L | Large SUV / 4WD |
| 15.0 L/100km | 15.7 mpg | 18.8 mpg | 6.7 km/L | Full-size truck, V8 performance |
| 20.0 L/100km | 11.8 mpg | 14.1 mpg | 5.0 km/L | Heavy-duty truck, large van |
Fuel economy unit conversions are needed every day by travellers, car buyers, engineers, and fleet managers operating across different countries. Here are the most common real-world scenarios.
Travellers from the US renting a car in Europe or Australia often encounter L/100km fuel economy figures on stickers and apps — completely unfamiliar to anyone used to mpg. Converting helps you judge whether a rental car is fuel-efficient and estimate your fuel costs. A car rated at 7 L/100km = approximately 33.6 mpg (US) — a perfectly respectable efficiency.
When buying a used Japanese import (rated in km/L), a European car (L/100km), or a US-spec vehicle (mpg US) outside its home market, you need to convert the fuel economy rating to your local standard for fair comparison. A Japanese car rated at 15 km/L = 35.3 mpg (US) = 6.67 L/100km — the same efficiency, three different numbers.
Fuel is sold in litres in most countries, but if your car's economy is rated in mpg, you need to convert to L/100km before calculating your cost per kilometre. For a trip of 500 km in a car using 8 L/100km, you need 40 litres. At $1.80/L that's $72 — easy to calculate once you've converted from mpg to L/100km.
CO₂ emissions are reported in grams per kilometre (g/km) in Europe, which links directly to L/100km. To compare the emissions of a US-spec car with a European model, you must convert mpg to L/100km first. As a rough guide, petrol combustion produces about 2.31 kg CO₂ per litre, so multiplying L/100km by 23.1 gives approximate CO₂ g/km.
Companies running mixed fleets — with US-spec trucks (mpg), European vans (L/100km), and Asian market vehicles (km/L) — must convert all units to a common standard to compare efficiency, set fuel budgets, and calculate total cost of ownership. Converting fuel economy per gallon to per litre is a daily task in international logistics and fleet operations.
Fuel economy unit conversion is a standard topic in physics, engineering, and environmental science courses. Students convert between mpg, km/L, and L/100km using dimensional analysis — applying conversion factors for length (miles ↔ km) and volume (gallons ↔ litres) simultaneously. It is also a common example in unit conversion coursework.
The US gallon (3.785 L) and the Imperial gallon (4.546 L) create significant differences in fuel economy comparisons. Always verify which standard is used when reading foreign car reviews or manufacturer specs. Imperial mpg is roughly 20% higher than US mpg for the same vehicle.
Energy Conversions →The US uses mpg (US gallon), the UK uses mpg (Imperial gallon), Europe and Australia use L/100km, Japan uses km/L, and China uses L/100km. This converter supports all major formats to make cross-market fuel economy comparisons fast and accurate.
More Converters →Once you've converted your fuel economy to L/100km, multiply by your trip distance (in 100 km units) to get total litres, then multiply by local fuel price per litre. For example: 500 km at 8 L/100km = 40 litres × $1.80/L = $72 total fuel cost.
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