Fuel Economy Converter (MPG to L/100km)

Convert between MPG (miles per gallon) and L/100km (liters per 100 kilometers) with this Fuel Economy Converter. Enter your fuel economy value, choose your conversion direction (MPG to L/100km or L/100km to MPG), and select whether you're using US or Imperial gallons. The converter instantly shows you the equivalent fuel economy in the other unit, so you can compare car specs across regions.

US gallon = 3.78541 L | Imperial gallon = 4.54609 L

Enter MPG or L/100km depending on your conversion direction

Results

Converted Fuel Economy

--

Kilometers per Liter

--

Efficiency Rating

--

Fuel Economy Comparison

Results Table

Frequently Asked Questions

What is MPG and how is it measured?

MPG stands for miles per gallon — the number of miles a vehicle can travel on one gallon of fuel. A higher MPG means better fuel efficiency and lower running costs. The US uses the US gallon (3.785 L), while the UK uses the Imperial gallon (4.546 L), so US and UK MPG figures are not directly comparable.

What is L/100km and why do some countries use it?

L/100km (liters per 100 kilometers) measures how many liters of fuel a vehicle consumes to travel 100 km. It is the standard fuel economy unit in most of Europe, Australia, and Canada. Unlike MPG, a lower L/100km value means better fuel efficiency.

How do I convert MPG to L/100km?

To convert US MPG to L/100km, divide 235.2145 by the MPG value. For example, 35 US mpg = 235.2145 ÷ 35 = 6.72 L/100km. For Imperial MPG, the constant is 282.481 instead of 235.2145, because the Imperial gallon is larger.

What is a good fuel economy figure?

For a typical passenger car, 35–45 US MPG (around 5–7 L/100km) is considered good fuel economy. Hybrid vehicles often achieve 50+ MPG (under 5 L/100km), while larger trucks or SUVs might return 15–25 MPG (9–16 L/100km). The 'good' threshold depends heavily on the vehicle class.

What is the difference between US MPG and UK (Imperial) MPG?

The key difference is the gallon size. A US gallon equals 3.785 liters, while an Imperial (UK) gallon equals 4.546 liters. This means a car rated at 40 UK MPG is actually less fuel-efficient than it sounds in US terms — 40 UK MPG is approximately 33 US MPG or 8.5 L/100km.

How do I convert L/100km back to MPG?

To convert L/100km back to US MPG, divide 235.2145 by the L/100km value. For example, 7 L/100km = 235.2145 ÷ 7 = 33.6 US MPG. The formula works in both directions because MPG and L/100km are inversely proportional.

How can I improve my car's fuel economy?

Key ways to improve fuel economy include maintaining steady speeds and avoiding aggressive acceleration, keeping tires properly inflated, reducing unnecessary weight in the vehicle, using the recommended engine oil, and ensuring the engine is well-serviced. Driving at highway speeds rather than stop-start city traffic also typically improves fuel efficiency.

Why do MPG and L/100km have an inverse relationship?

MPG measures how far you go per unit of fuel (distance ÷ fuel), while L/100km measures how much fuel you use per unit of distance (fuel ÷ distance). Because one is the reciprocal of the other, as MPG goes up, L/100km goes down. This is why you must use division rather than a simple multiplier to convert between them.

More Everyday Life Tools