Which volume units are used in the UK?

Litres and millilitres are the standard units, with the pint and gallon still in daily use. Fuel is sold by the litre, soft drinks and cooking oil come in litre and millilitre bottles, liquid medicines are measured in millilitres with a 5 ml spoon or oral syringe, and household water meters record cubic metres. Building materials such as concrete and topsoil are ordered in cubic metres too.

The pint survives where the law allows it or habit keeps it. Draught beer and cider are served in pints and fractions of a pint, doorstep milk in returnable bottles is sold by the pint, and supermarket milk is usually labelled with both, as in 4 pints (2.27 litres). Car fuel economy is still quoted in miles per gallon, even though nobody has bought petrol by the gallon for decades. The UK measurement system guide explains why these exceptions exist.

How do you convert pints to litres?

Multiply UK pints by 0.568 to get litres, or multiply litres by 1.76 to get UK pints. The exact size of a UK pint is 568.26125 ml, so 2 pints is 1.137 litres and a 4-pint bottle of milk holds 2.273 litres. To convert pints to millilitres, multiply by 568: half a pint is 284 ml.

UK pints	Litres	Litres	UK pints
½ pint	0.284 L (284 ml)	0.5 L	0.88 pints
1 pint	0.568 L (568 ml)	1 L	1.76 pints
2 pints	1.137 L	2 L	3.52 pints
4 pints	2.273 L	5 L	8.80 pints
6 pints	3.410 L	10 L	17.60 pints
8 pints (1 gallon)	4.546 L	20 L	35.20 pints

Why is a UK pint bigger than a US pint?

The two countries kept different gallons, and the pint is one eighth of each. Britain standardised the imperial gallon in 1824 and it is now defined as exactly 4.54609 litres. The United States kept an older wine gallon of 231 cubic inches, which is 3.785411784 litres. A UK pint (568.26 ml) is therefore about 20 per cent larger than a US liquid pint (473.18 ml).

Fluid ounces differ in the opposite direction. A UK pint contains 20 UK fluid ounces of 28.41 ml each, while a US pint contains 16 US fluid ounces of 29.57 ml each. So a US fluid ounce is slightly larger, even though the US pint is smaller. This matters for American recipes and for drinks bottles labelled in fluid ounces.

Unit	UK (imperial)	US (customary)
Fluid ounce	28.41 ml	29.57 ml
Pint	568.26 ml (20 fl oz)	473.18 ml (16 fl oz)
Quart	1.137 L (2 pints)	0.946 L (2 pints)
Gallon	4.546 L (8 pints)	3.785 L (8 pints)
Fluid ounces in 1 litre	35.2	33.8

How do you convert litres to gallons and mpg?

Divide litres by 4.546 to get UK gallons, or multiply UK gallons by 4.546 to get litres. A 50-litre fuel tank holds 11 UK gallons. If a figure comes from an American source, use 3.785 litres per US gallon instead, otherwise the answer will be about 20 per cent out.

Fuel economy is where the two gallons cause most confusion. UK cars are rated in miles per UK gallon, while much of Europe uses litres per 100 km. To convert, divide 282.48 by the UK mpg figure: 50 mpg is 5.65 L/100 km and 40 mpg is 7.06 L/100 km. A US mpg figure for the same car will be lower, because the US gallon is smaller. The litres to gallons converter handles both gallons.

What sizes are pub drinks in the UK?

Pub measures are fixed by law: beer and cider by fractions of a pint, spirits and wine in millilitres. Draught beer and cider are sold as a third of a pint (189 ml), half a pint (284 ml), two-thirds of a pint (379 ml) or multiples of half a pint. Gin, rum, vodka and whisky come in 25 ml or 35 ml measures, and still wine by the glass in 125 ml or 175 ml, or multiples of those. A standard 750 ml wine bottle is 1.32 UK pints.

How do cubic metres, litres and cc relate?

One litre is 1,000 cubic centimetres, and one cubic metre is 1,000 litres. A millilitre and a cubic centimetre (cc) are the same volume, which is why a 1,600 cc car engine is also described as a 1.6-litre engine. Capacity is simply the volume a container can hold, so the same units apply to tanks, fridges and storage boxes.

Volume	Equivalent	Everyday example
1 ml	1 cm³ (1 cc)	Dose marks on an oral syringe
5 ml	1 teaspoon	Standard medicine spoon
1 litre	1,000 cm³ = 1.76 UK pints	Carton of juice
28.32 litres	1 cubic foot	Freezer and fridge capacities in older listings
1 m³	1,000 litres = 220 UK gallons	Water meter reading, bulk bag of sand

Working out a volume from measurements is usually a matter of multiplying length by width by depth in the same unit. A tank 1 m × 0.5 m × 0.4 m holds 0.2 m³, which is 200 litres.

How much does a litre of water weigh?

A litre of water weighs almost exactly 1 kilogram. The original metric system linked the two on purpose, and at room temperature a litre of water has a mass of about 998 g, close enough to 1 kg for cooking and everyday use. A millilitre of water is therefore about 1 gram, which is why recipes often treat millilitres and grams of water as interchangeable.

Imperial units have a similar rule of thumb. A UK pint of water weighs about 568 g, or 1.25 lb, hence the old saying that “a pint of water weighs a pound and a quarter”. Oil, honey and flour do not follow this rule because their densities differ from water, so weigh them where accuracy matters.

What mistakes should you avoid when converting volumes?

Most volume errors come from mixing UK and US units. Check the source of any figure before you convert it:

• Using a US pint for a British recipe, or the reverse. Recipes from American websites use US pints, cups and fluid ounces. Converting them with UK factors adds about 20 per cent too much liquid.
• Treating fluid ounces as ounces. A fluid ounce is a volume and an ounce is a weight. They only line up for water and similar liquids.
• Comparing UK and US mpg directly. The same car shows a higher mpg figure in the UK than in the US, because a UK gallon is bigger.
• Mixing millilitres and centilitres. Some European bottles are labelled in centilitres: 75 cl is 750 ml.

Volume converters and guides in this section

New volume and capacity guides appear in the list below as they are published. These converters are available now:

• Volume converter: millilitres, litres, pints, gallons, fluid ounces and cubic units.
• Litres to gallons converter: fuel tanks, water butts and paint in UK or US gallons.
• Ml to fl oz converter: bottles, cosmetics and recipes in UK or US fluid ounces.
• Cooking converter: cups, tablespoons and teaspoons into millilitres and grams.

Latest volume and capacity guides

• How Many ml in a Tablespoon UK? 15 ml and Chart
• How Many ml in a Teaspoon UK? 5 ml Explained
• Litres to Pints UK: Converter and Printable Chart
• UK Fluid Ounce vs US Fluid Ounce: What’s the Difference?
• Imperial Gallon vs US Gallon: The Difference Explained
• UK Gallon in Litres: Converter, Chart and mpg Guide
• How Many ml in a UK Pint? Converter and Chart

Related sections

The units of measurement guide explains how the litre relates to the SI system. For recipes, see UK cooking measurements, and for converting ingredients by mass, see weight conversions.

Frequently asked questions

How many millilitres are in a UK pint?

A UK pint is 568 ml (568.26125 ml exactly). Half a pint is 284 ml.

How many pints are in a litre?

One litre is 1.76 UK pints, or 2.11 US pints. A litre is therefore a little less than two UK pints.

How many litres are in a UK gallon?

A UK gallon is 4.546 litres (4.54609 litres exactly) and contains 8 UK pints. A US gallon is smaller, at 3.785 litres.

How many millilitres are in a fluid ounce?

A UK fluid ounce is 28.41 ml and a US fluid ounce is 29.57 ml. There are 20 UK fluid ounces in a UK pint and 16 US fluid ounces in a US pint.

Is a cc the same as a millilitre?

Yes. One cubic centimetre (cc) is exactly one millilitre, so a 125 cc engine has a capacity of 125 ml and 1,000 cc is one litre.

Sources

• Weights and Measures Act 1985, Schedule 1 definitions of the gallon and pint, legislation.gov.uk
• Weights and measures: specified quantities, GOV.UK
• The International System of Units (SI Brochure), BIPM: the litre as a non-SI unit accepted for use with the SI
• National Institute of Standards and Technology (NIST), US customary unit definitions