The term “dram” is a historical unit of measure that refers to both a unit of mass and a unit of volume. Originating from the ancient Greek coin and weight called the drachma, the word evolved to signify a small quantity. This dual identity means that understanding how much is in a dram depends entirely on whether the context is weight, liquid volume, or a cultural reference. The technical definitions are rooted in historical systems of measurement, while its most common modern usage is a non-standardized, subjective measure, particularly in the world of spirits.
The Dram as a Unit of Mass
The dram was historically defined as a unit of weight within two distinct systems: the Apothecaries’ system and the Avoirdupois system. The Apothecaries’ system, primarily used for compounding medicines, defined the dram as a relatively heavier measure. Specifically, an Apothecaries’ dram is equal to one-eighth of an Apothecaries’ ounce, which translates to approximately 3.89 grams.
The Avoirdupois system, which is the basis for the common pound and ounce used today, assigned a much lighter value to the dram. In this system, the dram is defined as one-sixteenth of an Avoirdupois ounce. This Avoirdupois dram is equivalent to about 1.77 grams. While these units are largely obsolete, replaced by the metric system, their historical precision provides the literal answer to the question of the dram’s weight.
The Dram as a Unit of Volume
When referring to liquid, the unit is more accurately called the “fluid dram,” and its use was also historically tied to the Apothecaries’ system for measuring liquid medications. Like its mass counterpart, the fluid dram is not a single, universal measure but varies depending on the standard used, specifically between the United States and the Imperial system. In the United States, the fluid dram is defined as one-eighth of a US fluid ounce. This US fluid dram is equivalent to approximately 3.70 milliliters.
The Imperial fluid dram, used historically in the United Kingdom and its former colonies, is slightly smaller due to the difference in the size of the Imperial fluid ounce. The Imperial fluid dram is also one-eighth of an Imperial fluid ounce. This measure converts to approximately 3.55 milliliters. The distinction between the US and Imperial fluid drams highlights the complexity of historical measurements, where even the same fraction of a larger unit could differ based on geography.
The Dram in Whiskey Culture
The most common modern context for the term “dram” is in the enjoyment of spirits, particularly Scotch whisky, where it has shed its technical definition entirely. In this cultural setting, a dram is a subjective, colloquial term for a small serving or a taste of whisky. The term is deeply rooted in Scottish tradition, where it signifies a moment of conviviality and sharing.
When someone orders a “dram” in a bar or is offered a “wee dram,” the actual volume poured is determined by the establishment’s policy or the generosity of the person pouring. While some modern interpretations suggest a dram is roughly 25 to 35 milliliters, this is an informal range, not a rule. The term persists because it evokes a sense of warmth and tradition, referring to a modest, prized portion of the spirit.