Convert Ounces to Apothecary Ounces
Convert Ounces (oz) to Apothecary Ounces (oz ap) instantly and accurately.
Conversion Formula
oz ap = oz × 0.9114583333
About Ounces
The avoirdupois ounce (oz) is 1/16 of a pound, equal to approximately 28.35 grams. It is the everyday ounce used in the United States and United Kingdom for food portions, household quantities, and general trade. US food packages, recipe measurements, and nutrition labels reference ounces; a standard stick of butter is 4 oz, a can of soup typically 10.75 oz, and a baseball weighs 5-5.25 oz. Unlike the troy ounce (31.10 g) used for precious metals, the avoirdupois ounce (28.35 g) is lighter.
About Apothecary Ounces
An apothecary ounce (oz ap) is identical in mass to the troy ounce - approximately 31.10 grams - and equals 8 apothecary drams or 480 grains. It was the standard ounce used by pharmacists and physicians across Europe and North America from medieval times until the 20th century. Although the apothecary system has been replaced by SI units in modern medicine, the apothecary ounce still appears in historical pharmacopeias, traditional herbal medicine texts, and some compounding pharmacy references.
Quick Reference Table
| Ounces (oz) | Apothecary Ounces (oz ap) |
|---|---|
| 1 oz | 0.911458 oz ap |
| 2 oz | 1.82292 oz ap |
| 5 oz | 4.55729 oz ap |
| 10 oz | 9.11458 oz ap |
| 25 oz | 22.7865 oz ap |
| 50 oz | 45.5729 oz ap |
| 100 oz | 91.1458 oz ap |