MPG ↔ L/100km Converter

Convert fuel economy instantly between UK MPG (Miles per Gallon) and Litres per 100 kilometres (L/100km). Use this free calculator to compare vehicle fuel consumption, understand manufacturer fuel economy figures, and switch quickly between UK and metric fuel economy units.

✔ MPG ⇄ L/100km • ✔ UK & metric units • ✔ Fuel economy • ✔ Free converter

What this MPG ↔ L/100km Converter does

This free Fuel Economy Converter lets you quickly convert between UK MPG (Miles Per Gallon) and Litres per 100 kilometres (L/100km). Whether you're comparing vehicle specifications, checking manufacturer fuel economy figures, or planning running costs, this calculator provides instant and accurate conversions.

Unlike many online converters, this tool works in both directions. You can convert UK MPG to L/100km or convert L/100km back to UK MPG using the conversion buttons above.

The calculator also provides a simple fuel economy rating, helping you understand whether a vehicle's fuel consumption is considered Excellent, Very Good, Average, High, or Very High.

How to use this converter

1. Select the conversion direction.
2. Choose either MPG → L/100km or L/100km → MPG.
3. Enter your fuel economy value.
4. Click Convert.
5. View the converted value together with a fuel economy rating.

Understanding MPG and L/100km

Both measurements describe vehicle fuel economy but present the information differently.

• UK MPG measures how many miles a vehicle travels using one Imperial gallon of fuel. Higher MPG values indicate better fuel efficiency.
• L/100km measures how many litres of fuel are required to travel 100 kilometres. Lower values indicate better fuel efficiency.

Because one unit increases as efficiency improves while the other decreases, converting between them manually can be confusing. This converter performs the calculation instantly.

Conversion Formula

This calculator uses the standard UK (Imperial) conversion formula:

L/100km = 235.214 ÷ UK MPG

For the reverse calculation:

UK MPG = 235.214 ÷ L/100km

The constant 235.214 is based on the UK Imperial gallon (4.54609 litres).

UK MPG vs US MPG

UK MPG and US MPG are different measurements because the gallon sizes are different.

Measurement	Gallons Size
UK (Imperial) MPG	4.546 litres
US MPG	3.785 litres

This converter uses UK MPG only. If you are comparing fuel economy figures from North America, make sure they are first converted to UK MPG.

Fuel Economy Examples

UK MPG	L/100km	Efficiency
20	11.76	Very High Consumption
30	7.84	High
40	5.88	Average
50	4.70	Very Good
60	3.92	Excellent
70	3.36	Excellent

Typical Fuel Economy by Vehicle Type

Vehicle	Typical UK MPG
Small Petrol Car	50–70 MPG
Family Hatchback	40–60 MPG
Large Saloon	35–50 MPG
SUV	25–40 MPG
Van	25–45 MPG
Motorcycle	60–90 MPG

What affects real-world fuel economy?

Official manufacturer figures are measured under standard laboratory conditions. Your actual fuel economy can vary depending on:

• Driving style and acceleration.
• Average speed.
• Traffic congestion.
• Road conditions.
• Tyre pressure.
• Vehicle weight.
• Weather conditions.
• Vehicle maintenance.

Smooth driving, correct tyre pressures, and regular servicing can significantly improve real-world fuel efficiency.

When is this converter useful?

• Comparing vehicles before buying.
• Reading European vehicle specifications.
• Comparing UK and European fuel economy figures.
• Planning fuel costs for long journeys.
• Estimating running costs.
• Checking manufacturer fuel economy claims.

Frequently Asked Questions

Does this converter use UK or US MPG?
This calculator uses UK (Imperial) MPG, which is based on a 4.546-litre gallon.

Is higher MPG better?
Yes. A higher MPG value means your vehicle travels further using the same amount of fuel.

Is lower L/100km better?
Yes. Lower L/100km values indicate lower fuel consumption and better fuel efficiency.

Why are UK MPG and US MPG different?
The UK gallon is approximately 20% larger than the US gallon, so UK MPG values are higher for the same vehicle.

Can I use this calculator for petrol, diesel, hybrid and motorcycles?
Yes. The conversion is based purely on fuel economy measurements and works for any fuel-powered vehicle.

Does this calculator work for electric vehicles?
No. Electric vehicles usually measure efficiency in kWh per 100km or miles per kWh rather than MPG.

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