A quart is a unit of measurement for volume.
It is equal to two pints.
There are several different units known as a pint, and so there are accordingly several different quarts.
- US liquid measure:
- equal to two US liquid pints
- equal to four US liquid cups
- defined as one quarter of a US gallon
- equal to 32 US fluid ounces
- equal to 0.946352 litres
- US dry measure ("dry quart"):
- equal to two US dry pints
- defined as 1/32 of a US bushel
- equal to 67.2 cubic inches
- equal to 1.101220 litres
In imperial (UK & Canadian)
measure a quart is a measure of capacity, liquid or dry
- Imperial measure:
- equal to two imperial pints
- defined as one quarter of an imperial gallon
- equal to 40 imperial fluid ounces
- equal to 1.1365225 litre exactly
The UK legal definition of the (imperial) quart is 1.1365225 litres precisely in The Units of Measurement Regulations 1995
http://www.hmso.gov.uk/si/si1995/Uksi_19951804_en_2.htm
Reference
Guide for the Use of the International System of Units (SI)
US government publication; includes US-(liquid)-to-litre & imperial-to-litre conversion
Quart is also a municipality in Gironès comarca, Girona province, Catalonia, Spain.