according to the British Imperial system, the 1 fl ounce is equal to 0.00625 Imperial gallon and in the United States System of measurements the 1 fl ounce is 0.0075059 Liquid gallon. hence we can say that in 1 Imperial (U.K) gallon of water there are 160 fluid ounces and in 1 U.S gallon of water there are 133.3 fluid ounces
32 ounces is one quart, meaning one-quarter of a gallon.
64 ounces is a half-gallon, also known as two quarts.
96 ounces is three quarts.
16 ounces (half a quart) is one pint.
8 ounces (half a pint) is one cup.
All of this refers to measurements used in the USA. UK (Imperial) gallons and quarts are bigger than American ones.
Also, note that a fluid ounce (a unit of volume) is not necessarily the same as an ounce of weight.
Furthermore, dry quarts are not the same size as liquid quarts. The numbers I’ve given are for liquid measures.
The above may give you a hint as to why most countries have switched to the Metric (International) system of measurement.