Kilometers per Gallon (UK) (km/gal (UK)) - Unit Information & Conversion

Definition

Kilometers per Gallon (UK), often abbreviated as km/gal (UK), is a unit of fuel efficiency. It measures the distance in kilometers (km) that a vehicle can travel using one Imperial gallon (UK gal) of fuel. It combines a metric unit of distance with an Imperial unit of volume.

History

This unit is not a standard international unit for fuel consumption. Its use typically arises in specific contexts where metric distances (kilometers) need to be related to fuel volumes measured in Imperial gallons, which are still sometimes used in the UK and some Commonwealth countries, although less frequently for official fuel efficiency ratings today. It might appear when comparing vehicle specifications or fuel data across regions that use different systems or during transitions between measurement systems.

Common Uses

Kilometers per Gallon (UK) is rarely used in official vehicle specifications or everyday conversation. Standard units like Liters per 100 kilometers (L/100km), Miles per Gallon (UK MPG), or Kilometers per Liter (km/L) are far more common globally and within the UK itself. Its primary use might be in specific technical calculations, data conversions, or comparisons involving older data or equipment specified using Imperial gallons alongside metric distances.

Unit FAQs

Why is km/gal (UK) not commonly used?

Most countries and automotive manufacturers globally have standardized on either fully metric units (like km/L or L/100km) or, in specific regions like the US, customary units (MPG US). The UK predominantly uses MPG (UK) and increasingly L/100km. Hybrid units like km/gal (UK) introduce complexity and are generally avoided in official ratings and common usage to prevent confusion.

How does km/gal (UK) differ from km/gal (US)?

The key difference is the gallon size. The Imperial (UK) gallon is approximately 20% larger than the US gallon (1 UK gallon ≈ 4.546 liters, while 1 US gallon ≈ 3.785 liters). Therefore, for the same actual fuel efficiency, a vehicle's rating in km/gal (UK) will be numerically lower than its rating in km/gal (US) because it travels the same distance using a larger gallon measure.

How do I convert km/gal (UK) to km/L?

Divide the value in km/gal (UK) by the exact number of liters in an Imperial gallon: km/L = km/gal (UK) / 4.54609.

How do I convert km/gal (UK) to MPG (UK)?

Divide the value in km/gal (UK) by the exact number of kilometers in a mile: MPG (UK) = km/gal (UK) / 1.609344.

How do I convert km/gal (UK) to the common L/100km format?

Use the inverse relationship formula: L/100km = 454.609 / km/gal (UK). A higher km/gal (UK) value corresponds to a lower L/100km value (better fuel economy).