Convert Ounce to Dram (apothecary/troy)
Convert ounces to drams (apothecary/troy) instantly. 1 ounce = 7.2916666602 dram (apothecary/troy) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Dram (apothecary/troy) to Ounce converter for the reverse conversion.
Units explained
Ounce
The (avoirdupois) ounce (oz) equals one-sixteenth of a pound, about 28.35 grams.
From Latin 'uncia', meaning a twelfth part.
US food portions, postal weights, and boxing weight classes.
Standardized as 1/16 of the international pound from 1959.
Dram (apothecary/troy)
The apothecary (troy) dram equals one-eighth of a troy ounce, about 3.888 grams.
From the apothecaries' system rooted in the Greek 'drachma'.
Historical pharmacy and medicine compounding.
Part of the apothecaries' system of weights used through the 19th century.
Ounce to Dram (apothecary/troy) conversion formula
The relationship between ounces and drams (apothecary/troy):
To convert ounces to drams (apothecary/troy), multiply the value in ounces by 7.2916666602. To reverse, multiply drams (apothecary/troy) by 0.1371428573.
How to use this converter
Type a value into the calculator. The result in drams (apothecary/troy) updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Dram (apothecary/troy) to Ounce converter for the reverse direction.
Step-by-step: convert ounces to drams (apothecary/troy)
- Write down the value in ounces (oz).
- Multiply that value by the factor 7.2916666602.
- The product is the equivalent value in drams (apothecary/troy) (dr ap).
- To reverse, multiply the dram (apothecary/troy) value by 0.1371428573.
Worked examples
Example 1 — Convert 1 oz to dr ap:
1 × 7.2916666602 = 7.2916666602 dr ap
Example 2 — Convert 100 oz to dr ap:
100 × 7.2916666602 = 729.1666660237 dr ap
Real-world example — Ruler-scale measurements
A 30-ounce school ruler converts cleanly to drams (apothecary/troy) — useful when buying a desk accessory from a retailer whose product specs use a different unit.
30 oz × 7.2916666602 = 218.7499998071 dr ap
Real-world example — Hardware-scale dimensions
A 10-ounce fastener or component is about as long as a thumbnail. Mechanics and DIY enthusiasts convert between ounces and drams (apothecary/troy) daily when mixing metric and imperial tools.
10 oz × 7.2916666602 = 72.9166666024 dr ap
Real-world example — Postcard and small-object dimensions
A postcard is about 5 ounces wide. Converting to drams (apothecary/troy) is essential for international postal addressing forms that ask for dimensions in different units across countries.
5 oz × 7.2916666602 = 36.4583333012 dr ap
Ounce to Dram (apothecary/troy) conversion table
Standard reference values for converting ounces to drams (apothecary/troy):
| Ounce [oz] | Dram (apothecary/troy) [dr ap] |
|---|---|
| 0.01 | 0.0729166666 |
| 0.1 | 0.729166666 |
| 1 | 7.2916666602 |
| 2 | 14.5833333205 |
| 3 | 21.8749999807 |
| 4 | 29.1666666409 |
| 5 | 36.4583333012 |
| 10 | 72.9166666024 |
| 20 | 145.8333332047 |
| 30 | 218.7499998071 |
| 40 | 291.6666664095 |
| 50 | 364.5833330118 |
| 100 | 729.1666660237 |
| 500 | 3645.8333301183 |
| 1000 | 7291.6666602365 |
Frequently asked questions
How many drams (apothecary/troy) is 1 ounce?
How do I convert ounces to drams (apothecary/troy)?
How do I convert drams (apothecary/troy) back to ounces?
How many drams (apothecary/troy) is 100 ounces?
Popular weight unit conversions
Convert Ounce to other weight units
Show all Ounce conversions
Metric / SI (18 units)
Avoirdupois (14 units)
Troy & Apothecary (10 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 oz = 7.2916666602 dr ap) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.