What is Imperial gallon?

An Imperial gallon is a volume unit used in the United Kingdom equal to approximately 4.546 litres. It is larger than the US gallon and is commonly referenced for fuel efficiency (miles per gallon) in the UK.

Real-world uses

Imperial gallons are used in the United Kingdom, Canada (for some purposes), and several Caribbean countries. British fuel economy was historically quoted in miles per Imperial gallon. Older Commonwealth-era recipes and industrial specifications may reference Imperial gallons.

History

The Imperial gallon was established by the British Weights and Measures Act of 1824 as the volume occupied by 10 pounds of water at 62°F (≈ 17°C). It replaced several older gallon definitions including the wine gallon (retained by the US) and the ale gallon.

Common mistakes

Assuming the Imperial gallon equals the US gallon. The Imperial gallon is about 4.546 litres versus 3.785 litres for the US gallon. Converting mpg figures between the two systems without adjusting for gallon size gives misleading results.

What is cubic centimetre?

A cubic centimetre is a metric unit of volume equal to one thousandth of a litre, or 1 millilitre. It is used in medicine, engine displacement specifications, and precise scientific measurements.

Real-world uses

Cubic centimetres are used for engine displacement (e.g., a 250 cc motorcycle engine), medical syringe volumes (often marked "cc"), and laboratory measurements. Small container volumes and 3D printing material estimates are expressed in cm³.

History

The cubic centimetre was the standard volume unit in the CGS system. The abbreviation "cc" became entrenched in automotive and medical fields. The JCAHO (now The Joint Commission) recommended against "cc" in medical prescriptions to reduce errors, though it persists.

Common mistakes

Using "cc" interchangeably with mL is technically acceptable (they are equal), but some medical institutions discourage "cc" because it can be misread as "00" in handwritten prescriptions.

When is this conversion used?

Converting between Imperial gallon and cubic centimetre is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.

Worked examples

1 Imperial gallon = 4,546.09 cubic centimetre

1 cubic centimetre = 0.001 litre

How to convert Imperial gallon to cubic centimetre

To convert Imperial gallon to cubic centimetre, multiply the value by 4,546.09.

To convert cubic centimetre back to Imperial gallon, multiply by 0.00021997.

Measurement standards

The cubic metre is the SI derived unit of volume. The litre, equal to exactly one cubic decimetre (0.001 m³), is accepted by the BIPM for use alongside SI units. Both the lowercase "l" and uppercase "L" are approved symbols for the litre.

Did you know?

An Olympic swimming pool holds 2,500 cubic metres of water — about 2.5 million litres. The Amazon River discharges roughly 209,000 cubic metres per second, enough to fill 84 Olympic pools every single second.

Quick reference: Imperial gallon to cubic centimetre

Imperial galloncubic centimetre
0.1454.609
0.52,273.045
14,546.09
29,092.18
522,730.45
1045,460.9
25113,652.25
50227,304.5
100454,609
2501,136,522.5
5002,273,045
1,0004,546,090

Common values

Imperial galloncubic centimetre
A teaspoon0.00109985 Imperial gallon5 cubic centimetre
A cup of coffee0.05499231 Imperial gallon250 cubic centimetre
A water bottle0.10998462 Imperial gallon500 cubic centimetre
A bathtub65.99077449 Imperial gallon300,000 cubic centimetre
A swimming pool (Olympic)549,923.12074772 Imperial gallon2.500000e+09 cubic centimetre