DramEdit
Dram is a historical unit of measure that appears in more than one traditional system, serving as both a unit of mass and a unit of volume. In the avoirdupois system, the dram is a small mass unit defined as one sixteenth of an ounce. In the apothecaries' system, the dram is a larger mass unit equal to 60 grains, and there is also a fluid dram used for volume in that same tradition. Because of its multiple incarnations, dram figures prominently in old compendia of medicine, apothecaries’ recipes, and antique commercial ledgers, even as modern metric standards have largely displaced it in everyday use.
Historically, the term derives from the ancient weight tradition associated with the Greek drachma, passing through Latin and Old French into English. The word’s endurance reflects centuries of commerce, pharmacy, and domestic practice where small quantities mattered and precise fractions were practical for weighing herbs, minerals, and medicines. Today, the dram survives mainly in historical discussions and certain professional contexts, where traditional formulations and old texts still reference it. The modern, globally standardized system of measurement has shifted most usage away from the dram toward grams and liters.
Definitions and scope
Avoirdupois dram
In the avoirdupois system, the dram is defined as 1/16 of an avoirdupois ounce. This makes it the unit of mass for the casing and pricing of small quantities in some historical markets and older references. The avoirdupois ounce is defined as 28.349... g, so the avoirdupois dram is approximately 1.7718 g. Because there are 16 drams in an avoirdupois ounce and 16 ounces in a pound, there are 256 drams in a pound. For everyday practice, the avoirdupois dram is mostly of architectural interest today, appearing in antique recipes, old pharmacopoeias, and classic weight tables. See Ounce and Pound (mass) for related units.
Apothecaries’ dram
In the apothecaries’ (or troy) tradition of weight, the dram is equal to 60 grains. A grain is a small unit of weight, commonly defined as 1/7000 of a pound; in practical terms, 60 grains equals about 3.8879 g. This is the mass commonly called the “dram” in pharmacological and historical pharmaceutical contexts. The apothecaries’ system also includes a fluid dram for volume, used in compounding medicines. See Grain (weight) and Apothecaries' system for context, and Fluid dram for volume measurements.
Fluid dram
Separately, the fluid dram is a unit of volume used in the apothecaries’ system. It is defined as 1/8 of a fluid ounce in the US customary system, which equates to about 3.6967 milliliters. This unit is found in older medicinal recipes and labeling, and it coexists with the weight dram in historical pharmacopoeias. See Fluid ounce for broader context on liquid measures and Milliliter for modern equivalents.
History and usage
Dram appears in a lineage of weights and measures that emerged from ancient trade networks and evolving standardization efforts. The term entered English through the influence of medieval and early modern Latin and French usage, ultimately connecting to the ancient Greek weight unit drachma. In practice, the dram divided longer units into very small, manageable portions, which was valuable in medicine, perfumery, and early commerce.
In pharmacy and herbal medicine, the apothecaries’ dram served as a practical command for dosing, compounding, and labeling. The presence of a corresponding fluid dram facilitated preparations where volume and weight needed to be tracked together, such as tinctures and syrups. Over the 19th and 20th centuries, metric systems gained prominence in most jurisdictions, and the use of the dram declined in official contexts. Today, it survives mainly in historical texts, traditional recipes, and certain specialty areas where older conventions linger for reasons of fidelity to source material or regional habit. See Apothecaries' system and Mass for broader historical context.
The shift away from the dram reflects a broader trend toward universal metrication and the desire for unambiguous, easily convertible units in science, medicine, and international commerce. While the modern metric framework emphasizes grams and liters, the dram remains a touchstone for understanding how people measured small quantities in the past and how those practices shaped early modern economies and medical practice. See Grain (weight) and Scruple for related relics of the pre-metric era.
Etymology and related terms
The word dram traces to the ancient Greek drachma and reached English through Latin and Old French, preserving a sense of a small, carefully weighed amount. The various forms—avoirdupois dram, apothecaries’ dram, and fluid dram—illustrate how a single name adapted to different systems of measurement. See Drachma for the historical link to the ancient unit and Avoirdupois system for the modern English-speaking framework in which the term still appears in older texts.