Question: how much does fluid ounce of water weigh?
Answer: A U.S. fluid ounce of water will weight approx. 29.57 g, while 1 ounce of water will weigh 28.35 g, and an Imperial fluid ounce will weight approx. 28.4 g, which is only a difference from the avoirdupois ounce of water by 50 milligrams, which is an insignificant difference, especially for baking.