The US cup is a volume unit equal to 8 US fluid ounces or approximately 0.2366 liters, the standard measurement in American recipes and cookbooks. When a recipe calls for 'one cup of flour' or 'half a cup of sugar,' it refers to this specific volume, not a drinking vessel of arbitrary size. One US cup equals exactly 236.588 milliliters.

The US fluid ounce (fl oz) is a volume unit equal to approximately 29.574 milliliters, used to label beverages, cosmetics, and personal care products in the United States. Beverage cans, shampoo bottles, and skincare serums all display their contents in fluid ounces for American consumers. One fluid ounce equals exactly 1/128 of a US gallon or roughly 2 tablespoons.