Where the numbers come from
US butter is sold in standardized 4-ounce (113.4 g) sticks whose wrappers print tablespoon and cup gradations — 8 tbsp and 1/2 cup per stick. From that single definition every other factor follows: 1 cup = 2 sticks = 226.8 g, 1 tbsp = 14.175 g, and 1 oz = 28.3495 g (the avoirdupois ounce). Nothing here is estimated; all five units are anchored to grams and converted exactly.