Avoirdupois Ounce

A unit of weight equal to exactly 28.3495 grams, used in the US customary and British imperial systems for everyday goods.

Why it matters

When a recipe lists ingredient weights in ounces, it means avoirdupois ounces — not fluid ounces (volume) or troy ounces (precious metals). Avoirdupois is the standard for food, postage, and retail goods in the United States.

Examples

• A 6 oz block of chocolate weighs 6 × 28.3495 = 170.1 g.
• 16 avoirdupois ounces = 1 pound = 453.592 g.