Ancient unit of mass

• The Greek drachm is a weight of Greek mine, which is about 4.37 grams.
• The Roman drachm is a weight of Roman pounds, which is about 3.41 grams.

Greek and Roman drachm are related by the approximate ratio 25 : 32.

The Ottoman dirhem is based on the Sassanian drachm is itself based on the Roman dram/drachm. Modern Armenian drams, the currency of the Republic of Armenia, share this origin.

Modern unit of mass

The dram (symbol: ʒ) is also the mass of pound (℔) or ounce (℥) in the apothecaries' system that survived until the middle of the 20th century in English-speaking countries. It is equal to 3 scruples (℈) or 60 grains (G). Thus, it is equal to 3.888 grams (in the SI).

Unit of volume

The fluid dram is defined as of a fluid ounce, which means it is exactly equal to

• 3.696 691 195 312 5 mL in the United States and
• 3.551 632 812 500 0 mL in the Commonwealth and Ireland.

In the United Kingdom, a teaspoon was formerly defined as 1 fluid dram.

Dram is also used informally to mean a small amount of liquid, especially Scotch whisky.

See also

• Avoirdupois
• Imperial unit
• U.S. customary units