The US fluid ounce is a unit of volume in the US customary unit system with the symbol fl oz.
Primarily used for measuring the volume or capacity of liquids, 1 US fluid ounce is equal to 29.57353 ml. It is also equal to 1.040843 imperial fluid ounces.
1 US fluid ounce is equal to 1/16 imperial pint, 1/32 imperial quart and 1/128 imperial gallon.
The fluid ounce was originally defined by the volume taken up by one ounce of a substance. Of course this would be different depending on the density of that substance; for example England used wine whereas Scotland used water to establish this measure.
The US fluid ounce is derived from the US gallon; which was originally based on the English wine gallon (231 cubic inches).
The US liquid quart is a unit of volume in the US customary system with the symbol qt.
The US liquid quart is equal to 1/4 US liquid gallons, 2 US liquid pints, 4 US liquid cups, 8 US liquid gills or 32 US fluid ounces. The SI / metric equivalent is ≈ 0.946353 L.
The US liquid quart was based on exactly 57.75 in³ which was derived from the 1959 international yard and pound agreement whereby all traditional length and volume measures were legally standardised.