Ounces to Drams (oz to dr)

1 ounce equals 16 drams exactly.

1 ounce = 16 drams

How to convert ounces to drams

To convert ounces to drams, multiply the number of ounces by 16. This factor is exact. To go the other way, multiply drams by 0.0625.

drams = ounces × 16

Example: 10 ounces = 160 drams.

About these units

Ounce (oz)

US & ImperialCurrent unit

One sixteenth of a pound, exactly 28.349523125 g. Used for food, mail and consumer goods in the US and UK.

A twelfth part is what ounce originally meant. It comes from the Roman uncia, one twelfth of the Roman pound, a word that also gave English the inch. The abbreviation oz does not come from English at all but from the Italian onza or oncia. Over the centuries many regions and trades used different ounces: the English Tower ounce of 29.16 g was abolished by Henry VIII in 1527, and the Dutch ons was redefined as exactly 100 g in 1820.

The avoirdupois ounce used for everyday goods is one sixteenth of a pound, exactly 28.349523125 g or 437.5 grains, the standard in the US and under the UK imperial system. It is not the same as the troy ounce for precious metals, and neither is the fluid ounce, which measures volume. Ounces still describe portions such as steaks and burgers, and they show up in unexpected places: fabric is graded by weight per area, so a 16 oz denim is a heavy cloth, and the copper on a circuit board is specified in ounces, where 1 oz is roughly 34.7 micrometres thick.

1 ounce = 0.02834952313 kilograms (approximately).

Sources: Wikipedia: Ounce; NIST Guide to the SI, Appendix B.8 (mass conversions)

Dram (dr)

US & ImperialTraditional unit (still used in some regions)

One sixteenth of an ounce (1.7718 g). Used mainly for small quantities of powder.

Greek coinage lies behind this small weight: dram is a form of drachma, a coin that was also a unit of mass in ancient Greece. An Attic drachma weighed about 4.37 grams and a Roman one about 3.41 grams. The avoirdupois dram is smaller than both, one sixteenth of an ounce or one 256th of a pound, which is exactly 1.7718451953125 grams, or about 27.34 grains.

A different dram existed in medicine. The apothecaries' dram is an eighth of an apothecaries' ounce and equals 60 grains, or exactly 3.8879346 grams, and it was common in American pharmacy until the mid-twentieth century. After Britain's Weights and Measures Act 1878 the spellings split by about 1900, with dram for the avoirdupois unit and drachm for the apothecaries' one. Today the avoirdupois dram survives mainly in shotgun shell ratings, expressed in drams of black powder equivalent. As a loose word for a small measure of whisky, it has drifted away from the weight altogether.

1 dram = 0.001771845195 kilograms (approximately).

Sources: Wikipedia: Dram (unit)

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