What is MPG/L per 100km Converter?

This converter switches fuel efficiency values between miles per gallon (US and Imperial), liters per 100 kilometers, km/L, and miles per liter (mi/L). Type a number in any field and the others update instantly. A reference table shows typical figures for common vehicle types.

The relationship between MPG and L/100km is inverse, not linear, which trips a lot of people up. The converter handles both US gallons (3.785 L) and Imperial gallons (4.546 L), plus km/L and miles per liter for markets where those are the standard reading. A live efficiency rating (Excellent through Guzzler) and an EU-style A-to-G class sit next to the result, and an optional trip planner takes your tank size, fuel price, and annual mileage to project range, cost per 100 km, cost to fill up, yearly spend, and CO2 emissions. Vehicle reference values sit in a bar chart so you can compare at a glance.

How to use

1. Enter a fuel efficiency value in any supported unit: US MPG, Imperial MPG, L/100km, km/L, or mi/L.
2. See instant conversions to all other units — the relationship is inverse (higher MPG = lower L/100km).
3. Compare against the vehicle reference table and bar chart, or open the trip planner to estimate range, fuel cost, and CO2 from your tank size and yearly mileage.

When to use

• Comparing an American rental car's mpg sticker against a European model's L/100km figure.
• Reading a UK car review (Imperial MPG) and matching it to a US car spec (US MPG).
• Estimating fuel costs for a road trip when the rental brochure uses L/100km but you think in mpg.

Result

You're comparing a European car rated at 5.2 L/100km with an American one rated at 35 MPG (US). The converter shows 5.2 L/100km equals 45.2 US MPG -- so the European car uses noticeably less fuel.

FAQ

Why is converting MPG to L/100km not just simple division?

MPG measures distance per fuel unit while L/100km measures fuel per distance. The two are reciprocals, so doubling mpg roughly halves L/100km. The exact formula also has to convert gallons to litres and miles to kilometres.

What's the difference between US MPG and Imperial MPG?

An imperial gallon is 4.546 L while a US gallon is 3.785 L. The imperial gallon is bigger by about 20%, so the same car will show a higher MPG figure when measured in imperial. A 30 US MPG car reads around 36 imperial MPG.

Is the L/100km figure on my car's display accurate?

Most onboard computers are optimistic by a few percent because they don't account for cold-start enrichment or warm-up periods. Fill-up math (litres divided by km and multiplied by 100) gives the true number.

What counts as good fuel economy in 2026?

Under 6 L/100km (or above 40 US MPG) is competitive for a petrol-only car. Modern hybrids manage 4–5 L/100km, and plug-in hybrids drop below 2 L/100km on combined cycles if you charge regularly.

How do EV efficiency ratings compare with these units?

Electric cars don't burn fuel, so MPG and L/100km don't apply directly. The closest equivalents are MPGe (US) and kWh per 100 km (Europe). For rough comparison, 1 L of petrol is energy-equivalent to about 9 kWh.

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