Convert ounces to grams

Ounce

Definition

An ounce (symbol: oz) is a mass unit in the British Imperial and U.S. customary systems. The standard avoirdupois ounce is precisely 28.349523125 grams—exactly one-sixteenth of an avoirdupois pound.

Historical Overview

The term traces back to the Roman uncia (“twelfth part”), when a copper bar—defining both the Roman pound and foot—was divided into twelve equal unciae. Over centuries, regional variants appeared (for example, the Dutch ounce at 100 g, the French ~30.59 g, the Spanish ~28.75 g) until the modern ounce was internationally fixed in 1959.

Modern Usage

In the United States, ounces remain the go-to unit for measuring packaged foods, ingredients, postal items, and more. Though the United Kingdom has officially adopted metric measures, you’ll still encounter ounces in some restaurant menus and specialty contexts.

Gram

Definition

A gram (symbol: g) is an SI unit of mass, defined as one-thousandth of a kilogram—the SI’s base unit for mass. Since the 2019 redefinition, the kilogram is linked to Planck’s constant, and the gram inherits that exactness.

Historical Overview

Originally conceived as the mass of one cubic centimetre of water at 4 °C, the gram was part of the old CGS (centimetre-gram-second) system. As SI evolved, the gram was simply redefined as 0.001 kg to maintain coherence with the kilogram.

Modern Usage

Grams are universal in cooking, nutrition labels (per 100 g), laboratory measurements, and everyday commerce around the globe.

Ounce → Gram Conversion Table

How to Convert

• 1 oz = 28.349523125 g

• 1 g = 0.0352739619 oz

Example

To convert 15 oz to grams:

15 oz × 28.349523125 = 425.2428 g