MPG Calculator — Miles Per Gallon UK
Calculate fuel efficiency, fuel cost per mile, convert MPG to l/100km, and estimate journey costs.
Last updated: February 2025 | Author: Mustafa Bilgic (MB)
MPG Calculator
Enter the distance you drove and the fuel used to calculate your MPG.
Enter your MPG and fuel price to find the cost of driving per mile or kilometre.
UK average petrol price approx. 143–150p/litre (Feb 2025). Diesel approx. 147–155p/litre.
Convert between UK MPG and litres per 100km (l/100km). Uses UK Imperial gallon (4.54609 litres).
Calculate the total fuel cost for a road trip or commute.
UK Average MPG by Car Type (2025)
| Car Category | Typical Real-World MPG | l/100km | Example Models |
|---|---|---|---|
| Small City Car (Petrol) | 45–55 MPG | 5.1–6.3 | VW Polo, Ford Fiesta, Vauxhall Corsa |
| Family Hatchback (Petrol) | 38–50 MPG | 5.7–7.4 | VW Golf, Ford Focus, Toyota Auris |
| Family Saloon/Estate (Diesel) | 45–60 MPG | 4.7–6.3 | BMW 3 Series, Ford Mondeo, Skoda Octavia |
| SUV (Petrol) | 28–40 MPG | 7.1–10.1 | Nissan Qashqai, Kia Sportage, BMW X3 |
| SUV (Diesel) | 38–50 MPG | 5.7–7.4 | Land Rover Discovery Sport, Volvo XC60 |
| Petrol-Electric Hybrid | 50–70 MPG | 4.0–5.7 | Toyota Prius, Honda Jazz Hybrid, Yaris Hybrid |
| Plug-in Hybrid (PHEV) | 100–300 MPG* | varies | Mitsubishi Outlander PHEV, BMW 530e |
| Sports Car (Petrol) | 20–35 MPG | 8.1–14.1 | Porsche 911, Ford Mustang, BMW M3 |
| Van (Diesel) | 28–40 MPG | 7.1–10.1 | Ford Transit, VW Transporter, Mercedes Sprinter |
*PHEV official MPG is unreliable as it depends heavily on how often the battery is charged. Real-world MPG with an uncharged battery is much lower.
What is MPG and How is it Measured?
Miles per gallon (MPG) is the primary measure of fuel efficiency used in the United Kingdom. Unlike most of Europe, which uses litres per 100 kilometres (l/100km), the UK has historically used the Imperial measurement system and continues to measure fuel economy in MPG. It represents how many miles a vehicle can travel on one UK (Imperial) gallon of fuel.
The UK gallon — also called the Imperial gallon — contains 4.54609 litres. This is different from the US gallon, which contains only 3.78541 litres, which is why UK and US MPG figures for the same car are different even when the underlying fuel consumption is identical.
Official UK MPG figures are now measured using the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) test cycle, which replaced the older NEDC test in 2018. WLTP figures are generally more realistic than NEDC, but real-world fuel economy can still vary significantly from official figures depending on driving style, traffic conditions, road type and weather.
How to Calculate Your Real-World MPG
The most accurate way to measure your car's true fuel consumption is the brim-to-brim method:
- Fill your tank completely to the brim
- Reset your trip odometer to zero (or note the current odometer reading)
- Drive normally until your fuel light comes on or until you want to refuel
- Fill up again and note exactly how many litres you put in
- Note the miles driven since you last filled up
- Calculate: MPG = Miles driven ÷ (Litres added ÷ 4.54609)
Repeat this process over several fill-ups and calculate the average for a more accurate long-term figure, as a single tank can be skewed by whether you did mostly motorway or city driving.
MPG to l/100km Conversion Formula
The conversion formula between UK MPG and litres per 100km is based on the relationship between miles, kilometres, and the UK gallon:
- 1 mile = 1.60934 kilometres
- 1 UK gallon = 4.54609 litres
- Therefore: l/100km = (4.54609 × 100) ÷ (1.60934 × MPG) = 282.48 ÷ MPG
For example: 40 MPG = 282.48 ÷ 40 = 7.06 l/100km. Conversely, 8 l/100km = 282.48 ÷ 8 = 35.3 MPG.
How to Convert MPG
This converter provides instant, accurate results for your measurement conversions. The UK uses a mix of metric and imperial measurements in daily life, which can make conversions a frequent necessity. Road signs use miles, food is sold in grams and kilograms, and height is often quoted in feet and inches despite the metric system being the official standard.
Understanding the conversion formula helps verify results and perform quick mental calculations when a tool is not available.
Key Information
Common UK conversion factors: 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 mile = 1.609 km, 1 pound (lb) = 0.4536 kg, 1 stone = 6.35 kg, 1 pint (UK) = 568 ml, 1 gallon (UK) = 4.546 litres, 1 acre = 0.4047 hectares. Temperature conversions use the formula: Celsius = (Fahrenheit - 32) x 5/9.
Example Calculation
To convert 5 feet 10 inches to centimetres: first convert to total inches (5 x 12 + 10 = 70 inches), then multiply by 2.54 to get 177.8 cm. For weight, a person weighing 12 stone 7 lbs is 12.5 stone, which equals 79.4 kg (12.5 x 6.35).
Source: Based on international measurement standards. Last updated March 2026.
Frequently Asked Questions
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