A measurement of 50 milliliters is equivalent to 1.6907 U.S. fluid ounces. U.S. fluid ounces is slightly different from imperial ounces, with 1 U.S. fluid ounce measuring 29.5735295625 milliliters in the International System of Units to 28.4130625 milliliters in 1 imperial ounce.
The fluid ounce is different from the ounce, which is used to measure mass. However, the term fluid ounce may be shortened to just ounce when the context makes its meaning obvious. Traditionally, the fluid ounce refers to the volume occupied by liquid substances such as wine and water in the United Kingdom. The ounce used for these measurements were varied as and is dependent on the liquid that is being measured such ounces for measuring wine or ounces for measuring ale.
The ounce was standardized in 1824 by the British Parliament with the imperial gallon being the volume of 10 pounds of water. The gallon is divisible into 4 quarts,the quart can be divided into 2 pints, the pint into 4 gills and the gill into 5 ounces.
The U.S. fluid ounce on the other hand based from the U.S. gallon, which is derived from the wine gallon that measures 231 cubic inches. It was the wine gallon measurement used in England before the standardization in 1824. The U.S. fluid ounce is 1/128 parts of a U.S. gallon.