Fluid Ounce

The fluid ounce (abbreviated as fl oz) is a standard unit of volume measurement used primarily for liquids in the United States. One US fluid ounce is equivalent to 1/8 of a US cup, 2 tablespoons, or approximately 29.57 milliliters. It is critical to distinguish the fluid ounce, which measures volume (space occupied), from the dry ounce (oz), which measures weight (mass). For water and liquids of similar density, like milk or juice, one fluid ounce weighs approximately one ounce. However, for denser liquids like honey, molasses, or maple syrup, a fluid ounce weighs significantly more than a dry ounce due to the higher specific gravity of these ingredients.

In professional settings, recipes list liquids in fluid ounces or milliliters to eliminate confusion. When measuring fluid ounces in the kitchen, always use a clear liquid measuring cup placed on a level surface, and read the measurement at the bottom of the meniscus (the curved surface of the liquid) at eye level. Using dry measuring cups for fluid ounces is inaccurate because they lack a pouring spout and are difficult to fill to the exact brim without spilling.