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 teaspoon (metric)?

A metric teaspoon is a volume unit equal to exactly 5 millilitres. It is a standard unit in cooking recipes and pharmaceutical dosing instructions across metric countries.

Real-world uses

The metric teaspoon (5 mL) is used in cooking recipes, pharmaceutical dosing instructions, and nutrition labelling. It is the standard dosing spoon for children's liquid medicines. Most international recipes specify teaspoon measurements assuming the 5 mL metric standard.

History

The teaspoon originated as a unit of apothecary measure in the 18th century, roughly the volume of a small spoon used to stir tea. The metric teaspoon was standardized at exactly 5 mL to align with the metric system and simplify pharmaceutical dosing.

Common mistakes

Confusing the metric teaspoon (5 mL) with the US customary teaspoon (4.929 mL) or the older Imperial teaspoon (3.55 mL). Also, using a household spoon instead of a measuring spoon—actual spoons vary widely in size.

When is this conversion used?

Converting Imperial gallon to teaspoon (metric) is useful in the volume domain when comparing values across different measurement standards or applying formulas that require a specific unit.

Worked examples

1 Imperial gallon = 909.218 teaspoon (metric)

1 teaspoon (metric) = 0.005 litre

How to convert Imperial gallon to teaspoon (metric)

To convert Imperial gallon to teaspoon (metric), multiply the value by 909.218.

To convert teaspoon (metric) back to Imperial gallon, multiply by 0.00109985.

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 teaspoon (metric)

Imperial gallonteaspoon (metric)
0.190.9218
0.5454.609
1909.218
21,818.436
54,546.09
109,092.18
2522,730.45
5045,460.9
10090,921.8
250227,304.5
500454,609
1,000909,218

Common values

Imperial gallonteaspoon (metric)
A teaspoon0.00109985 Imperial gallon1 teaspoon (metric)
A cup of coffee0.05499231 Imperial gallon50 teaspoon (metric)
A water bottle0.10998462 Imperial gallon100 teaspoon (metric)
A bathtub65.99077449 Imperial gallon60,000 teaspoon (metric)
A swimming pool (Olympic)549,923.12074772 Imperial gallon500,000,000 teaspoon (metric)

Available Volume units

More Imperial gallon conversions