Dram

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The dram (archaic spelling drachm; apothecary symbol ℨ) was historically both a coin and a weight. Currently it is both a small mass in the Apothecaries' system of weights and a small unit of volume. This unit is called more correctly fluid dram or in contraction also fluidram.

Ancient unit of mass

• The Greek drachm is a weight of ¹⁄₁₀₀ Greek mine, which is about 4.37 grams.
• The Roman drachm is a weight of ¹⁄₉₆ 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

In the avoirdupois system, the dram is the mass of ¹⁄₂₅₆ pound or ¹⁄₁₆ ounce. So the dram weighs ⁸⁷⁵⁄₃₂ grains or exactly 1.771 845 195 3125 grams.

The dram (symbol: ʒ) is also the mass of ¹⁄₉₆ pound (℔) or ¹⁄₈ 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 exactly 3.887 9346 grams.

Unit of volume

The fluid dram is defined as ¹⁄₈ 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 3/2 fluid dram.

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

"Dram" is also used as a measure of the powder charge in a shotgun shell.

See also

Look up dram in Wiktionary, the free dictionary.

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