- How do you measure 16 oz of water?
The straight answer is there are 8 US fluid ounces in a cup, so 16 US fluid ounces would be equal to 2 cups (aka 1 pint or 1/2 quart). In the world of US weights, since "A pint's (quite nearly) a pound the world around", 16 troy ounces of water is just a bit less than 2 cups.

- How do you measure 16 ounces?
In the US a standard cup measure = 8 FLUID oz (abbrev. fl. oz) of VOLUME. If by 16 oz you mean the US VOLUME, equal to 1 PINT US, then 2 cups.