Quart

A quart (qt) is a unit of volume in the U.S. customary and imperial systems of measurement. The definition of a quart is based on the gallon; 1 quart is a quarter of a gallon, hence the name. This means that the actual volume is dependent on the definition of the gallon. In terms of milliliters:

1 quart (US) = 946.353 mL

1 quart (imperial) = 1136.523

Many different definitions of the gallon (and therefore quart) have been used in the past, but the definitions above are two that are still in use.

US vs imperial quarts

A quart is just one unit of volume in the US customary and imperial systems of measurement that is defined relative to the gallon. A few others include the pint, cup, and gill. The relationships between these units are the same in both systems of measurement.

Although the relationships above are the same in both the US customary and imperial systems of measurement, both systems use different definitions of a gallon. As such, a quart is a quarter of a gallon in both systems, but the actual measurement of each quart is different. They are typically compared in terms of milliliters. Since 1 US gallon is equal to 3,785.412 mL and 1 imperial gallon is equal to 4,546.092 mL:

US customary system:

• 1 quart = 946.353 mL
• 1 pint = 473.177 mL
• 1 cup = 236.589 mL
• 1 gill = 118.295 mL

Imperial system:

• 1 quart = 1136.523 mL
• 1 pint = 568.262 mL
• 1 cup = 284.131 mL
• 1 gill = 142.065 mL

The US further differentiates quarts into liquid quarts and dry quarts:

US liquid quart = 946.353 mL

US dry quart = 1101.221 mL

Knowing (or referencing) the above relationships allows us to convert between various units of measurement. This is important because it allows people around the world to communicate measurements even if different measurement systems are used.