Apothecary Weights and Measures: Historical Symbols and Conversions

Updated for accuracy and usability (Aug 2025). If you’re translating historical recipes or herbals and keep bumping into ℈ ʒ ℥, this page is your friend. Below you’ll find corrected gram values, a quick converter, and a few notes on look-alike units that trip people up.

Jump to: Symbols & Table · Conversion Notes · Example · Glossary (variable units) · FAQ · Sources

Apothecary’s balance and weights, Young & Son, London (Wellcome Collection, CC-BY 4.0).

Apothecary Weight Symbols

Quick copy symbols:

Unit	Symbol	Modern Equivalent (by weight)
Grain	gr	0.0648 g (64.8 mg)
Scruple	℈	1.296 g (20 grains)
Dram (apothecary)	ʒ	3.888 g (3 scruples = 60 grains)
Ounce (apothecary)	℥	31.103 g (8 drams = 480 grains)
Pound (apothecary)	lb (lib.)	373.242 g (12 ounces)
Quarter	qr.	≈93.3 g (3 ounces)
Half-quarter	s.	≈46.65 g (1½ ounces)

📏 Quick Converter

Convert grams ↔ scruples/ drams using standard apothecaries’ weight.

Grams:

Scruples (℈):

Conversion Notes

• 1 lb (lib.) = 12 ℥ (ounces)
• 1 ℥ (ounce) = 8 ʒ (drams)
• 1 ʒ (dram) = 3 ℈ (scruples)
• 1 ℈ (scruple) = 20 grains
• Grain → gram: grain × 0.06479891
• Note: The apothecary ounce differs from the avoirdupois ounce used in kitchens; don’t mix them.

Example Conversion

A medieval receipt calls for “2 ℈ saffron.” That equals:
2 × 1.296 g = 2.592 grams.

Frequently Confused Units

• ʒ (dram) can mean weight (apothecary) or volume (“fluid dram”) in some texts—watch context.
• ℥ (ounce) here is apothecary weight, not kitchen/avoirdupois.
• An̄ / ana means “of each, in equal quantity” (equal parts), not a specific weight.

Herbs Commonly Dispensed by Unit

Historical information only; not medical advice.

• Grains: Opium poppy, belladonna, digitalis—high-potency items in micro-doses.
• Scruples: Rue, hyssop, saffron—antidotes, tonics, or coloring agents.
• Drams: Wormwood, valerian root, fennel—digestive bitters or nervines.
• Ounces: Chamomile, horehound, licorice root—infusions, decoctions, syrups.

Glossary: Variable / Contextual Historical Units

These appear in period sources but aren’t part of the standardized apothecaries’ weight. Values vary by time/place and source; treat them as contextual, not fixed gram equivalents.

• manipulus (handful) — a handful of a herb; inherently approximate.
• aureus — literally “gold piece”; sometimes used as a comparative weight or coin, not a standard apothecary unit.
• obolus — a classical coin/weight term with shifting values; avoid assigning a single gram number.
• siliqua — “carob seed”; used as a seed-weight in Roman measures, not fixed in later texts.
• an̄ / ana — “of each (equally)”; an instruction for equal parts.

🔎 Explore More Historical Conversions

• Medieval Measurements and Conversions
• Ounce to Tablespoon Conversion FAQ (Dry)
• Spice Conversions: Ounces to Tablespoons
• Feast Budgeting & Cost per Person Guide

How period cooks measured, converted, and planned for feasts—using both modern tools and historical math.

Sources and References

• Wikipedia: Apothecaries’ system
• RF Cafe: Apothecary & Avoirdupois Conversions
• Culinary Lore: Carat and Carob Seeds
• Wiktionary: Siliqua
• Prepositas His Practise (1600s Medical Manual)
• Zupko, Ronald E. “Medieval Apothecary Weights and Measures.” Pharmacy in History 32.2 (1990): 57–62. JSTOR