An avoirdupois pound is exactly 0.45359237 kilograms.
Pounds to Drams Converter — lb to dr
Convert Pound (lb) to Dram (dr) using the exact conversion factor (1 pound = 256 dram). See the formula, worked examples, conversion table, history, and common uses.
Pounds to Drams converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
An avoirdupois dram is 1/16 ounce.
Result = input x 0.45359237 / 0.001771845195.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Pounds to Drams
Weight conversions between Pound and Dram come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Pound is most often used for body weight and food retail packaging in the united states.
Formula
drams = pounds × 256
This factor comes from each unit's defined relationship to the category's base unit: 1 pound equals 0.45359237 base units, and 1 dram equals 0.00177184519531 base units, so dividing one by the other gives the direct pound-to-dram factor of 256.
Simple example
1 lb × 256 = 256 dr
1 pound = 256 drams.
Real-world example
50 lb × 256 = 12,800 dr
50 pounds = 12,800 drams.
Conversion table
| Pound (lb) | Dram (dr) |
|---|---|
| 1 lb | 256 dr |
| 5 lb | 1,280 dr |
| 10 lb | 2,560 dr |
| 25 lb | 6,400 dr |
| 50 lb | 12,800 dr |
| 100 lb | 25,600 dr |
Reverse conversion: Dram to Pound
256 dr × 0.00390625 = 1 lb
256 drams = 1 pound.
pounds = drams × 0.00390625
For a page dedicated to this direction, see Dram to Pound.
Understanding the Pound
Pound (lb) measures mass. The avoirdupois pound is legally defined as exactly 0.45359237 kilograms, fixed by international treaty in 1959. It is classified as a US/imperial customary unit.
Where it's used: United States (primary mass/weight unit) United Kingdom (informal and some retail use) Various Caribbean and Pacific territories with historical UK/US ties
Pound-mass vs. pound-force. This page converts pound-mass (lbm), a unit of mass. Pound-force (lbf) is a separate unit measuring the force gravity exerts on one pound-mass, used in engineering contexts like pounds per square inch.
Uses of the Pound today
- Body weight and food retail packaging in the United States
- Postal, parcel, and freight weight in US shipping and logistics
- Pound-force (lbf) and its derivatives (psi, foot-pounds) in US engineering and aerospace
History of the Pound
Unlike the kilogram's single documented birth in revolutionary France, the pound's history is a long, layered narrowing of competing regional standards. The avoirdupois pound — ancestor of today's standard — emerged among London merchants in the early 14th century (recorded use around 1303), used for weighing wool and other bulk goods under the system merchants called 'avoir de pois,' Old French for 'goods of weight.' Its 16-ounce structure suited large-scale trade better than the 12-ounce troy pound used for precious metals.
Wool merchants used a related 'wool pound' of about 6,992 grains — close enough to 7,000 that Elizabeth I's government formally fixed the avoirdupois pound at exactly 7,000 grains in 1588, the value still used today. Britain and the US then refined their physical standards separately over the following centuries, leaving small discrepancies between them.
Those discrepancies were resolved on 1 July 1959, when the US, UK, Canada, Australia, New Zealand, and South Africa signed the International Yard and Pound Agreement, fixing the pound at exactly 0.45359237 kg and the yard at exactly 0.9144 m. The US National Bureau of Standards (now NIST) adopted the value immediately; the UK followed via its Weights and Measures Act 1963 — the value used by virtually every country today.
Historical origin. Pound was not the invention of a single named person; it developed through the process described above.
Understanding the Dram (dr)
An avoirdupois dram is 1/16 ounce.
Pound — sources
- NIST — International yard and pound, Federal Register notice (1959) — Official 1959 refinement of the yard and pound values adopted by the US National Bureau of Standards.
- Encyclopaedia Britannica — 'Pound (unit of weight)' — History of the Tower, troy, and avoirdupois pounds and their standardization in England.
- UK Weights and Measures Act 1963, s.1(1) — Statutory UK definition of the pound as exactly 0.45359237 kilogram.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many drams are in 1 pound?
1 pound equals 256 drams, using the exact defined conversion factor rather than an estimate.
How do I convert pound to dram?
Multiply the pound value by 256. The converter above does this instantly to whatever precision you set.
How do I convert dram back to pound?
Use the reverse factor: 1 dram equals 0.00390625 pounds. You can also use the swap control in the converter above to flip the direction instantly.
What is a pound?
Pound (lb) measures mass. The avoirdupois pound is legally defined as exactly 0.45359237 kilograms, fixed by international treaty in 1959. It is classified as a US/imperial customary unit.
What is a dram?
Dram (dr) is a unit of mass/weight.
Is the pound to dram conversion exact?
Yes. The avoirdupois pound is legally defined as exactly 0.45359237 kilograms, fixed by international treaty in 1959. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between pound-mass vs. pound-force?
This page converts pound-mass (lbm), a unit of mass. Pound-force (lbf) is a separate unit measuring the force gravity exerts on one pound-mass, used in engineering contexts like pounds per square inch.
Where is the pound still used today?
United States (primary mass/weight unit) United Kingdom (informal and some retail use) Various Caribbean and Pacific territories with historical UK/US ties