Ounces to Milligrams

Ounce

An ounce (oz) is a small US customary unit of weight equal to 1/16 of a pound, or about 28.35 grams. It is commonly used in cooking, portion sizes, mail weighing, and food packaging. Ounces provide a practical scale for items too small for pounds but too large for grams alone.

Although the same word, ounce, also refers to a liquid measurement (fluid ounce), the two units are completely different. This converter focuses on ounces used for weight.

Milligram

A milligram (mg) is a very small metric unit of mass equal to one-thousandth of a gram. It is commonly used in medicine, nutrition, and science to measure tiny quantities where precision is crucial. Vitamins, pharmaceuticals, and food additives often list dosage amounts in milligrams because even a small difference can matter.

Milligrams help prevent rounding errors when grams would be too large of a unit. While metric conversions are simple — 1,000 milligrams in a gram — switching to ounces or pounds requires careful calculation, making a converter especially useful.