Ounce to Dram Converter

Convert ounces to drams with our free online weight converter.

Quick Answer

1 Ounce = 16 drams

Formula: Ounce × conversion factor = Dram

Use the calculator below for instant, accurate conversions.

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All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: December 2025|Reviewed by: Sam Mathew, Software Engineer

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How to Use the Ounce to Dram Calculator:

Enter the value you want to convert in the 'From' field (Ounce).
The converted value in Dram will appear automatically in the 'To' field.
Use the dropdown menus to select different units within the Weight category.
Click the swap button (⇌) to reverse the conversion direction.

How to Convert Ounce to Dram: Step-by-Step Guide

Converting Ounce to Dram involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Ounce = 16 drams

Example Calculation:

Convert 5 ounces: 5 × 16 = 80 drams

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

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What is a Ounce and a Dram?

The ounce (symbol: oz, from Italian onza) is a unit of mass equal to exactly 1/16 of an avoirdupois pound, which is 28.349523125 grams in the metric system.

Avoirdupois Ounce vs. Troy Ounce

When Americans say "ounce" in everyday life, they almost always mean the avoirdupois ounce (28.35 g). However, there's a second type of ounce:

Avoirdupois Ounce (Standard Ounce):

28.35 grams
Used for: food, cooking, postal weight, groceries, body weight, general commerce
16 ounces = 1 avoirdupois pound

Troy Ounce:

31.10 grams (about 10% heavier)
Used exclusively for: precious metals (gold, silver, platinum), gemstones, gunpowder
12 troy ounces = 1 troy pound
Abbreviated: "oz t" or "ozt"

Critical distinction: When buying gold or silver, prices are quoted per troy ounce (31.1 g), not avoirdupois ounce (28.35 g). A troy ounce is about 2.75 grams heavier than a standard ounce.

Ounce vs. Fluid Ounce

This is one of the most common sources of confusion in American cooking:

Ounce (oz): Measures weight/mass

Used for solid or bulk ingredients: flour, sugar, meat, cheese
1 oz = 28.35 grams
Measured with a scale

Fluid Ounce (fl oz): Measures volume/capacity

Used for liquids: water, milk, juice, oil
1 fl oz = 29.57 milliliters (US) or 28.41 mL (UK)
Measured with measuring cups

When they happen to match: For pure water at room temperature, 1 fluid ounce weighs approximately 1 ounce. This coincidence often misleads people into thinking oz and fl oz are interchangeable—they're not.

Example of the difference:

8 fl oz of water weighs about 8 oz
8 fl oz of honey weighs about 12 oz (honey is denser)
8 fl oz of olive oil weighs about 7.3 oz (oil is less dense)

Mathematical Relationships

1 ounce equals:

1/16 of a pound (exactly)
28.349523125 grams (exactly)
0.028349523125 kilograms
437.5 grains (grain is an even smaller unit)
28,349.523125 milligrams

Common fractions of a pound:

1 oz = 1/16 lb = 0.0625 lb
4 oz = 1/4 lb = 0.25 lb (quarter-pound)
8 oz = 1/2 lb = 0.5 lb (half-pound)
12 oz = 3/4 lb = 0.75 lb
16 oz = 1 lb (full pound)

Avoirdupois Dram (Commercial)

The avoirdupois dram is defined in the common weight system used for most goods:

Relationships:

1 dram = 1/16 ounce (avoirdupois)
1 dram = 1/256 pound (avoirdupois)
1 dram = 27.34375 grains (exactly)
1 dram ≈ 1.7718451953125 grams (exactly)

Symbol: dr, dr av, or dr avdp

Historical use: General commerce, precious materials, spices, ammunition powder charges.

Apothecary/Troy Dram (Pharmaceutical)

The apothecary dram (also called drachm) belongs to the apothecaries' weight system used historically in pharmacy:

Relationships:

1 dram (ʒ) = 1/8 ounce (apothecary)
1 dram = 3 scruples
1 dram = 60 grains (exactly)
1 dram ≈ 3.8879346 grams (exactly)

Symbol: ʒ (resembles the number 3, representing 3 scruples)

Historical use: Compounding medicines, pharmaceutical measurements, medical prescriptions.

The Critical Difference

Apothecary dram = 2.194 × Avoirdupois dram

This 2.2× ratio causes confusion. Historical recipes and medical texts must specify which system they use, or dosages could be dangerously incorrect.

Fluid Dram (Volume, Not Weight)

Adding to the confusion, the fluid dram is a unit of volume:

Fluid dram (imperial):

1/8 fluid ounce (imperial)
≈ 3.5516 mL

Fluid dram (US):

1/8 fluid ounce (US)
≈ 3.6967 mL

Symbol: fl dr, fl ʒ, or ℈

This is completely separate from weight drams, though historically related (1 fluid dram of water weighs approximately 1 avoirdupois dram).

Note: The Ounce is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Dram belongs to the imperial/US customary system.

History of the Ounce and Dram

Roman Origins: The Uncia

Latin Etymology: The word "ounce" comes from the Latin "uncia," meaning "one-twelfth" (related to "inch," from the same root).

Roman Measurement: In ancient Rome, the uncia was 1/12 of a Roman pound (libra), approximately 27 grams. The Romans used base-12 (duodecimal) systems for many measurements.

Symbol Origin: The abbreviation "oz" comes from the medieval Italian word onza (ounce), not from any English word starting with "o" and "z."

Medieval European Variation

Regional Chaos: Throughout medieval Europe, dozens of different "ounces" existed, varying by region, city, and trade guild. An ounce in Paris differed from an ounce in London, Venice, or Amsterdam.

Two Main English Systems:

Troy System (for precious goods):

Used for gold, silver, jewels, and later gunpowder
Troy ounce: 31.1 grams
12 troy ounces = 1 troy pound
Named after Troyes, France, site of important medieval trade fairs

Avoirdupois System (for bulk goods):

From French avoir de pois ("goods of weight")
Used for wool, grain, cheese, meat—everyday bulk commodities
Avoirdupois ounce: 28.35 grams
16 avoirdupois ounces = 1 avoirdupois pound
Developed by medieval merchants for practical trade

English Standardization

1300s-1500s: Gradual Standardization: English monarchs attempted to standardize weights and measures, but variation persisted.

1588: Queen Elizabeth I: Confirmed the avoirdupois system for general trade, establishing 16 ounces per pound for commerce.

Troy System Preserved: The troy ounce remained the standard for precious metals, a tradition maintained to this day.

1959: International Agreement

Modern Definition: The 1959 international yard and pound agreement between the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa defined:

1 pound (avoirdupois) = exactly 453.59237 grams
1 ounce (avoirdupois) = exactly 1/16 pound = 28.349523125 grams

This eliminated minor variations between US and British measurements and anchored imperial units to the metric system.

Ancient Greek Drachma (600 BCE - 300 CE)

The drachma coin: Greek city-states minted silver coins called drachmas, weighing approximately 4.3 grams (varying by region and period).

Origin of name: "Drachma" (δραχμή) derives from "drax" (handful) or "drassomai" (to grasp), possibly referring to a handful of six obol coins.

Weight standard: The Attic drachma (Athens) weighed about 4.3 g of silver, becoming a widespread weight and monetary standard.

Roman Adoption (300 BCE - 500 CE)

Drachma in Roman medicine: Roman physicians adopted Greek medical practices, including pharmaceutical measurements based on the drachma.

Galen's formulations: The physician Galen (129-216 CE) used drachmas extensively in medicinal recipes, establishing the unit in medical tradition.

Byzantine and Islamic Medicine (500-1200 CE)

Byzantine continuation: The Eastern Roman Empire (Byzantium) preserved Greek medical texts, maintaining the drachm as a pharmaceutical unit.

Islamic Golden Age: Arab physicians (Al-Razi, Avicenna) translated Greek medical works, incorporating drachms into Arabic pharmacy. The dirham (Arabic coin) shares the same etymological root.

Transmission to Europe: Through Islamic Spain and Sicily, Arabic medical knowledge returned to Western Europe (11th-13th centuries), bringing pharmaceutical drachm measurements.

Medieval European Apothecaries (1200-1600)

Apothecary guilds: European cities established apothecary guilds, standardizing medicinal weights based on the drachm.

The apothecary system:

1 pound (lb ap) = 12 ounces
1 ounce (℥) = 8 drams (ʒ)
1 dram = 3 scruples (℈)
1 scruple = 20 grains (gr)

Result: 1 apothecary dram = 60 grains

Symbol evolution: The symbol ʒ (scribal abbreviation for Latin "drachma") became standard for the dram.

British Standardization (1600-1800)

London Pharmacopoeia (1618): The first official British pharmacopoeia standardized apothecary weights, including the dram at 60 grains.

Avoirdupois emergence: Simultaneously, the avoirdupois system developed for general commerce, creating a different dram:

Avoirdupois dram = 1/16 ounce = 27.34375 grains

Coexistence: Two dram standards coexisted—apothecary for medicine, avoirdupois for trade.

American Adoption (1776-1900)

U.S. Pharmacopeia (1820): The first U.S. Pharmacopeia codified pharmaceutical measurements, adopting British apothecary standards including the dram.

Medical education: American medical schools taught apothecary measurements. Physicians wrote prescriptions using symbols like ʒ for drams.

Commercial use: Avoirdupois drams measured gunpowder, spices, precious materials, and other commodities.

Ammunition Application (1800s-Present)

Black powder charges: Early firearms used black powder measured in drams. A "3-dram load" meant 3 avoirdupois drams of powder.

Dram equivalent: With the transition to smokeless powder (1880s onward), manufacturers created "dram equivalent" ratings—the amount of smokeless powder producing the same velocity as a given dram measure of black powder.

Modern shotshells: Today's shotgun shells still reference "3 dram equivalent" or "3¼ dram equivalent" on the box, though actual powder weights are in grains or grams.

Metrication and Decline (1900-Present)

British pharmacy (1970): The UK officially abandoned apothecary weights, switching entirely to metric (grams, milligrams).

American pharmacy (1970s-1980s): U.S. pharmacy schools phased out apothecary measurements, adopting metric. By 1990, nearly all prescriptions used metric units.

Persistence:

Ammunition: Dram equivalent ratings continue
Historical recipes: Antique cookbooks and medical texts
Collectors: Antique apothecary scales and weights

Common Uses and Applications: ounces vs drams

Explore the typical applications for both Ounce (imperial/US) and Dram (imperial/US) to understand their common contexts.

Common Uses for ounces

Cooking and Baking

Recipe Measurements: American recipes commonly specify ingredient weights in ounces:

Dry ingredients: flour, sugar, chocolate chips, nuts
Solid fats: butter, shortening, cream cheese
Proteins: chicken breasts (6 oz), ground beef (12 oz)

Kitchen Scales: Digital kitchen scales display weight in ounces (and grams), allowing precise measurement:

Toggle between oz and g
Tare function to zero out container weight
Precision to 0.1 oz or 1 gram

Baker's Preference: Professional bakers prefer weight (ounces) over volume (cups) because:

More accurate and consistent
Eliminates measurement errors
Works regardless of how ingredients settle or compact

Grocery Shopping and Pricing

Price per Pound, Sold by Ounce: Many items are priced per pound but sold in ounce quantities:

Deli meat: "$8.99/lb, customer orders 6 oz"
Cheese: "$10.99/lb, customer gets 4 oz"
Bulk nuts: "$12.99/lb, customer takes 8 oz"

Nutrition Labels: US food labels show serving size in both household measures and ounces:

"Serving Size: 3/4 cup (30g, about 1 oz)"
This allows people to weigh food if they don't have measuring cups

Comparison Shopping: Savvy shoppers compare unit prices (price per ounce) to find better deals:

Large box cereal: $0.25/oz
Small box cereal: $0.35/oz
Buying larger sizes often reduces cost per ounce

Postal Services and Shipping

USPS Pricing Tiers: First-Class Mail costs increase per ounce:

0-1 oz: $0.68 (2024 rate)
1-2 oz: $0.92
2-3 oz: $1.16
3-3.5 oz: $1.40

Package Weight Categories:

Under 1 pound: priced per ounce
Over 1 pound: typically priced per pound

Shipping Strategy: Sellers carefully package items to stay under weight thresholds, sometimes removing extra packaging to save an ounce.

Precious Metals and Jewelry

Troy Ounce Standard: Gold, silver, platinum, and palladium are traded globally in troy ounces:

Gold price: "$2,050 per troy ounce" (example)
Silver price: "$25 per troy ounce" (example)
Bullion bars marked in troy ounces (1 oz, 10 oz, etc.)

Jewelry Weights: Precious metal jewelry is often described by weight:

"14K gold chain, 0.5 troy oz"
"Sterling silver bracelet, 1.2 troy oz"

Investment: Investors buy gold/silver coins and bars measured in troy ounces (1 oz American Gold Eagle, 5 oz silver bar).

Medical and Healthcare

Infant Weight: Hospitals and pediatricians measure newborn weight in pounds and ounces:

Birth weight: "7 pounds 6 ounces"
Weight checks: tracking gains of 4-6 oz per week
Feeding goals: "baby should gain 5-7 oz weekly"

Medication Dosing: Some medications dose by body weight:

Pediatric doses calculated per pound or per ounce
Conversion to metric (kg) for precise dosing

Nutrition and Dietetics: Dietitians often recommend portion sizes in ounces:

"3 oz serving of protein" (deck of cards size)
"1 oz serving of cheese" (pair of dice size)

Portion Control and Diet

Standard Serving Sizes:

Meat/fish: 3-4 oz (cooked)
Cheese: 1-1.5 oz
Nuts: 1 oz (small handful)
Pasta: 2 oz dry per serving
Cereal: 1 oz (varies by type; check label)

Visual Cues for Ounces:

3 oz meat = deck of playing cards
1 oz cheese = pair of dice
1 oz nuts = small handful
2 oz pasta = fits in cupped palm

When to Use drams

1. Ammunition and Reloading

Shotshell ratings: Manufacturers mark shotgun shells with "dram equivalent" to indicate approximate velocity/power level.

Why still used? Tradition and familiarity. Shooters understand "3 dram load" means standard power, while "3¾ dram" is heavy magnum.

Reloading manuals: Some reloading data references dram equivalents alongside modern grain measurements.

2. Historical Recipe Interpretation

19th-century cookbooks: Recipes may call for "1 dram of nutmeg" or "2 drams of ginger."

Conversion challenge: Must determine if the recipe uses avoirdupois or apothecary drams (usually avoirdupois for cooking).

Modern equivalent: 1 avoirdupois dram ≈ 1.77 grams ≈ 1/3 teaspoon (for dry spices)

3. Antique Apothecary Items

Collectible scales: Antique apothecary scales often have dram weights marked with ʒ.

Medicine bottles: Historical pharmacy bottles may indicate contents in drams.

Historical research: Understanding drams is essential for interpreting 18th-19th century medical texts.

4. Pharmaceutical History

Old pharmacopoeias: Historical pharmaceutical formulas use apothecary drams.

Example prescription (1850s): "℞ Quinine sulfate ʒij" = Take 2 drams of quinine sulfate

Modern interpretation: 2 apothecary drams = 7.78 grams

Additional Unit Information

About Dram (dr)

How many drams are in an ounce (avoirdupois)?

Exactly 16 avoirdupois drams = 1 avoirdupois ounce.

This is the definition:

1 oz av = 16 dr av
1 dr av = 1/16 oz av = 0.0625 oz

How many grams are in a dram (avoirdupois)?

1 avoirdupois dram = 1.7718451953125 grams (exactly).

Practical approximation: 1 dr av ≈ 1.77 g

Derivation: 1 pound av = 453.59237 grams (exact) 1 pound = 256 drams 1 dram = 453.59237 ÷ 256 = 1.77185 g

Is a dram a unit of mass or volume?

Both exist, which causes significant confusion:

Mass (weight):

Avoirdupois dram (dr): 1.772 g
Apothecary dram (ʒ): 3.888 g

Volume:

Fluid dram (fl dr, US): 3.697 mL
Fluid dram (fl dr, imperial): 3.552 mL

Context matters:

Pharmacy/medicine historically: could be either (check symbols)
General commerce: usually weight
Modern usage: rare except ammunition (weight-related rating)

What's the difference between avoirdupois and apothecary drams?

Avoirdupois dram (commercial):

1/16 ounce avoirdupois
27.34375 grains
1.772 grams
Used for general goods

Apothecary dram (pharmaceutical):

1/8 ounce apothecary
60 grains
3.888 grams
Used for medicines

Key difference: Apothecary dram is 2.19× heavier than avoirdupois dram.

What does the symbol ʒ mean?

The symbol ʒ represents the apothecary dram.

Origin: Scribal abbreviation of Latin "drachma" or "dragma."

Appearance: Resembles a fancy number "3," which is appropriate since 1 dram = 3 scruples.

Usage: Historical pharmaceutical prescriptions: "℞ Morphine ʒi" = Take 1 dram of morphine

What is a dram equivalent in ammunition?

"Dram equivalent" is a velocity/power rating for shotgun shells, not actual powder weight.

Historical context: Black powder shotgun loads used actual drams of powder (e.g., "3 drams of black powder").

Modern meaning: A "3 dram equivalent" smokeless powder load produces approximately the same muzzle velocity as a historical 3-dram black powder load.

Actual powder weight: Modern "3 dram equivalent" loads typically contain 18-22 grains of smokeless powder (less than 1 actual dram by weight).

Rating scale:

2¾ dram eq: Light/target
3 dram eq: Standard
3¼ dram eq: Magnum
3¾ - 4 dram eq: Heavy magnum

Do doctors still use drams?

No, modern medicine uses metric units exclusively.

Historical use: 19th and early 20th century physicians wrote prescriptions using apothecary measurements including drams (ʒ).

Transition:

UK: Abandoned apothecary units in 1970
US: Phased out 1970s-1990s

Current practice: All modern prescriptions use milligrams (mg), grams (g), and milliliters (mL). Drams are historical artifacts.

How do I convert historical dram measurements?

Step 1: Identify the system

Pharmacy/medicine: Likely apothecary dram (3.888 g)
Cooking/commerce: Likely avoirdupois dram (1.772 g)

Step 2: Check for symbols

ʒ symbol: Definitely apothecary
"dr" or no symbol: Context-dependent (probably avoirdupois for cooking)

Step 3: Convert to grams

Avoirdupois: drams × 1.772
Apothecary: drams × 3.888

Step 4: Convert to modern measure

Grams to teaspoons (dry ingredients): ~5 g per tsp
Grams to milliliters (liquids): depends on density

Can I still buy dram weights?

Yes, as antique collectibles, but not for practical use.

Antique apothecary weights: Available from antique dealers, often brass or bronze, marked with ʒ symbol.

Modern equivalents: Not manufactured. Use gram scales instead.

Collectible value: Complete sets of 18th-19th century apothecary weights command $100-500+ depending on condition.

Why did pharmacy abandon drams?

Multiple reasons drove metrication:

1. International standardization: Metric system adopted globally for science and medicine.

2. Safety: Multiple dram systems (avoirdupois vs. apothecary) created dangerous confusion.

3. Ease of calculation: Decimal metric system simpler than fractional apothecary system.

4. Precision: Milligrams allow more precise dosing than grains/scruples/drams.

Result: By 1990, virtually all pharmacy worldwide used metric exclusively.

Conversion Table: Ounce to Dram

Ounce (oz)	Dram (dr)
0.5	8
1	16
1.5	24
2	32
5	80
10	160
25	400
50	800
100	1,600
250	4,000
500	8,000
1,000	16,000

How do I convert Ounce to Dram?

To convert Ounce to Dram, enter the value in Ounce in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our weight converter page to convert between other units in this category.

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What is the conversion factor from Ounce to Dram?

The conversion factor depends on the specific relationship between Ounce and Dram. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Dram back to Ounce?

Yes! You can easily convert Dram back to Ounce by using the swap button (⇌) in the calculator above, or by visiting our Dram to Ounce converter page. You can also explore other weight conversions on our category page.

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What are common uses for Ounce and Dram?

Ounce and Dram are both standard units used in weight measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our weight converter for more conversion options.

For more weight conversion questions, visit our FAQ page or explore our conversion guides.

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