Convert Pennyweight to Dram (apothecary/troy)
Convert pennyweights to drams (apothecary/troy) instantly. 1 pennyweight = 0.3999999897 dram (apothecary/troy) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Dram (apothecary/troy) to Pennyweight converter for the reverse conversion.
Units explained
Pennyweight
The pennyweight (dwt) equals one-twentieth of a troy ounce, 24 grains (about 1.555 g).
From the mass of a medieval English silver penny; symbol dwt from 'denarius weight'.
Jewelry making and precious-metal scrap valuation in the US.
Derived from the medieval English coinage system.
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.
Pennyweight to Dram (apothecary/troy) conversion formula
The relationship between pennyweights and drams (apothecary/troy):
To convert pennyweights to drams (apothecary/troy), multiply the value in pennyweights by 0.3999999897. To reverse, multiply drams (apothecary/troy) by 2.5000000643.
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 Pennyweight converter for the reverse direction.
Step-by-step: convert pennyweights to drams (apothecary/troy)
- Write down the value in pennyweights (dwt).
- Multiply that value by the factor 0.3999999897.
- The product is the equivalent value in drams (apothecary/troy) (dr ap).
- To reverse, multiply the dram (apothecary/troy) value by 2.5000000643.
Worked examples
Example 1 — Convert 1 dwt to dr ap:
1 × 0.3999999897 = 0.3999999897 dr ap
Example 2 — Convert 100 dwt to dr ap:
100 × 0.3999999897 = 39.9999989712 dr ap
Real-world example — Ruler-scale measurements
A 30-pennyweight 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 dwt × 0.3999999897 = 11.9999996914 dr ap
Real-world example — Hardware-scale dimensions
A 10-pennyweight fastener or component is about as long as a thumbnail. Mechanics and DIY enthusiasts convert between pennyweights and drams (apothecary/troy) daily when mixing metric and imperial tools.
10 dwt × 0.3999999897 = 3.9999998971 dr ap
Real-world example — Postcard and small-object dimensions
A postcard is about 5 pennyweights wide. Converting to drams (apothecary/troy) is essential for international postal addressing forms that ask for dimensions in different units across countries.
5 dwt × 0.3999999897 = 1.9999999486 dr ap
Pennyweight to Dram (apothecary/troy) conversion table
Standard reference values for converting pennyweights to drams (apothecary/troy):
| Pennyweight [dwt] | Dram (apothecary/troy) [dr ap] |
|---|---|
| 0.01 | 0.0039999999 |
| 0.1 | 0.039999999 |
| 1 | 0.3999999897 |
| 2 | 0.7999999794 |
| 3 | 1.1999999691 |
| 4 | 1.5999999588 |
| 5 | 1.9999999486 |
| 10 | 3.9999998971 |
| 20 | 7.9999997942 |
| 30 | 11.9999996914 |
| 40 | 15.9999995885 |
| 50 | 19.9999994856 |
| 100 | 39.9999989712 |
| 500 | 199.9999948559 |
| 1000 | 399.9999897118 |
Frequently asked questions
How many drams (apothecary/troy) is 1 pennyweight?
How do I convert pennyweights to drams (apothecary/troy)?
How do I convert drams (apothecary/troy) back to pennyweights?
How many drams (apothecary/troy) is 100 pennyweights?
Popular weight unit conversions
Convert Pennyweight to other weight units
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Metric / SI (18 units)
Avoirdupois (15 units)
Troy & Apothecary (9 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 dwt = 0.3999999897 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.