A standard cup contains 8 fluid ounces for liquid measurements according to the U.S. system. For dry ingredients, a cup's weight in ounces can vary depending on the ingredient density, but commonly it is about 4.5 ounces by weight. Here are some key points:

• 1 cup = 8 fluid ounces (liquids)
• 1 cup ≈ 4.5 dry-weight ounces (varies by ingredient)
• Common smaller conversions: ½ cup = 4 fluid ounces, ¼ cup = 2 fluid ounces, etc.

The distinction is that fluid ounces measure volume (liquids), while ounces as a weight unit apply to dry ingredients and depend on their density.