MPG to km/l Converter
Convert miles per gallon to kilometres per litre instantly. This converter supports both UK and US gallons, giving you precise fuel efficiency measurements for any vehicle. Whether you’re comparing cars across different markets or planning a trip abroad, get your conversion in seconds.
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MPG to km/l Conversion Table
Here’s a reference table showing common MPG values converted to kilometres per litre for both UK and US gallons. Use this for quick lookups when comparing vehicle specifications.
| MPG (UK) | km/l | MPG (US) | km/l |
|---|---|---|---|
| 20 | 7.08 | 20 | 8.50 |
| 25 | 8.85 | 25 | 10.63 |
| 30 | 10.62 | 30 | 12.75 |
| 35 | 12.39 | 35 | 14.88 |
| 40 | 14.16 | 40 | 17.01 |
| 45 | 15.93 | 45 | 19.13 |
| 50 | 17.70 | 50 | 21.26 |
| 55 | 19.47 | 55 | 23.38 |
| 60 | 21.24 | 60 | 25.51 |
| 65 | 23.01 | 65 | 27.63 |
| 70 | 24.78 | 70 | 29.76 |
| 75 | 26.55 | 75 | 31.89 |
| 80 | 28.32 | 80 | 34.01 |
Conversion Formulas
Converting between MPG and km/l requires different formulas depending on which gallon measurement you’re starting with. The UK Imperial gallon is larger than the US gallon, which affects the conversion factor.
UK Imperial Gallon Conversions
MPG (UK) to km/l:
km/l = MPG (UK) × 0.354006
km/l to MPG (UK):
MPG (UK) = km/l ÷ 0.354006
Example: A car achieving 45 MPG (UK) equals 45 × 0.354006 = 15.93 km/l
US Gallon Conversions
MPG (US) to km/l:
km/l = MPG (US) × 0.425144
km/l to MPG (US):
MPG (US) = km/l ÷ 0.425144
Example: A vehicle rated at 35 MPG (US) equals 35 × 0.425144 = 14.88 km/l
Step-by-Step Conversion Process
- Identify whether your MPG value uses UK Imperial or US gallons
- Select the appropriate conversion factor (0.354006 for UK, 0.425144 for US)
- Multiply your MPG value by the conversion factor
- Round the result to two decimal places for practical use
- Remember that higher km/l values indicate better fuel efficiency
UK vs US vs Metric Measurements
Fuel efficiency measurements vary globally, creating confusion when comparing vehicles from different markets. Each system has its own logic and history.
UK Imperial System
Unit: Miles per gallon (MPG)
Gallon size: 4.54609 litres
Usage: United Kingdom, some Commonwealth countries
Typical range: 30-60 MPG for modern cars
US System
Unit: Miles per gallon (MPG)
Gallon size: 3.78541 litres
Usage: United States
Typical range: 25-50 MPG for modern cars
Metric System
Unit: Kilometres per litre (km/l) or litres per 100km (L/100km)
Volume: Litre (1.0 L)
Usage: Most of Europe, Asia, Australia
Typical range: 10-20 km/l for modern cars
Why the Difference Matters
A car advertised as achieving 40 MPG could mean two different things. In UK terms, that’s 14.16 km/l. In US terms, it’s 17.01 km/l. That’s a significant difference when you’re making purchasing decisions or estimating running costs.
Most European and Asian markets use L/100km rather than km/l. This inverted measurement (fuel consumed per distance rather than distance per fuel) makes it easier to calculate trip costs. Lower numbers indicate better efficiency in this system.
Fuel Efficiency Context
Understanding what constitutes good fuel economy helps you make informed decisions when buying or running a vehicle.
Current UK Benchmarks
The average new car in the UK achieves approximately 38.6 MPG (13.67 km/l) across all fuel types. Petrol vehicles typically return around 36 MPG (12.74 km/l), whilst diesel models average 43 MPG (15.22 km/l). Modern hybrids can exceed 60 MPG (21.24 km/l), with some plug-in hybrids reaching 70+ MPG in mixed driving.
- Below 35 MPG (12.39 km/l): Below average efficiency, often seen in larger SUVs, performance cars, or older vehicles
- 35-45 MPG (12.39-15.93 km/l): Average range for most family cars and medium-sized vehicles
- 45-60 MPG (15.93-21.24 km/l): Good efficiency, typical of economical diesels and small petrol cars
- 60-75 MPG (21.24-26.55 km/l): Excellent efficiency, achieved by hybrids and ultra-efficient models
- Above 75 MPG (26.55 km/l): Outstanding efficiency, usually plug-in hybrids in electric mode
Practical Examples
A Toyota Prius hybrid achieves roughly 94 MPG (33.28 km/l) in optimal conditions. The Peugeot 208 diesel returns around 73.6 MPG (26.05 km/l). Popular family cars like the Ford Focus typically deliver 40-50 MPG (14.16-17.70 km/l) depending on the engine.
Related Fuel Economy Conversions
Fuel efficiency can be expressed in multiple ways depending on the region and preference. Here are the most common alternative measurements.
| From | To | Multiply By |
|---|---|---|
| MPG (UK) | L/100km | 282.481 ÷ MPG |
| MPG (US) | L/100km | 235.215 ÷ MPG |
| km/l | L/100km | 100 ÷ km/l |
| MPG (UK) | MPG (US) | 1.20095 |
| MPG (US) | MPG (UK) | 0.832674 |
| L/100km | km/l | 100 ÷ L/100km |
FAQs
For UK gallons, multiply 40 by 0.354006 to get 14.16 km/l. For US gallons, multiply 40 by 0.425144 to get 17.01 km/l. Always specify which gallon type you’re converting from to avoid confusion.
Neither is inherently better; they’re just different ways to express the same thing. MPG is traditional in the UK and US, whilst km/l is used in countries with the metric system. Both measure how far you can travel per unit of fuel. Many argue L/100km is more intuitive for cost calculations.
The difference lies in gallon sizes. A UK Imperial gallon contains 4.54609 litres, whilst a US gallon contains only 3.78541 litres. Since the UK gallon is roughly 20% larger, a vehicle achieves approximately 20% higher MPG in UK measurements compared to US measurements for the same fuel consumption.
For most cars, 12-15 km/l represents average efficiency, 15-20 km/l is good, and anything above 20 km/l is excellent. Small city cars and hybrids often exceed these figures, whilst larger vehicles and performance cars typically achieve lower numbers.
Yes, but be aware that European specifications often use L/100km instead. To convert, divide 100 by the L/100km figure. For example, 5.0 L/100km equals 20 km/l (100 ÷ 5.0 = 20). Lower L/100km numbers mean better efficiency.
Absolutely. Aggressive acceleration, high speeds, and frequent braking can reduce fuel efficiency by 15-30%. Gentle acceleration, maintaining steady speeds, and anticipating traffic flow can significantly improve your vehicle’s real-world fuel economy compared to official figures.
Official figures often reflect ideal laboratory conditions rather than real-world driving. Actual fuel economy typically runs 10-20% lower than advertised, depending on driving conditions, vehicle load, weather, and individual driving habits. The newer WLTP testing procedure is more realistic than the old NEDC system.
Converting to a familiar unit helps you compare vehicles fairly across different markets. If you’re used to UK MPG, converting foreign specifications to that standard (or to km/l as a neutral comparison point) ensures you’re making like-for-like comparisons when evaluating options.