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.

The teaspoon (tsp) is the smallest standard cooking volume unit, equal to approximately 4.929 milliliters, found in recipes worldwide for measuring small quantities of spices, extracts, and medicine. It serves as the building block for larger measurements, with three teaspoons making one tablespoon. One US teaspoon equals exactly 1/6 of a US fluid ounce.