An avoirdupois pound is exactly 0.45359237 kilograms.
Pounds to Stones Converter — lb to st
Convert Pound (lb) to Stone (st) using the exact conversion factor (1 pound = 0.0714285714 stone). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Pounds to Stones converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
A stone is 14 pounds.
Result = input x 0.45359237 / 6.35029318.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Pounds to Stones
Weight conversions between Pound and Stone 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 typically associated with united States (primary mass/weight unit), while Stone is typically associated with united Kingdom and Ireland (body weight).
Formula
stones = pounds × 0.0714285714286
This factor comes from each unit's defined relationship to the category's base unit: 1 pound equals 0.45359237 base units, and 1 stone equals 6.35029318 base units, so dividing one by the other gives the direct pound-to-stone factor of 0.0714285714286.
Simple example
1 lb × 0.07142857143 = 0.0714285714 st
1 pound = 0.0714285714 stones.
Real-world example
50 lb × 0.07142857143 = 3.571428571 st
50 pounds = 3.571428571 stones.
Conversion table
| Pound (lb) | Stone (st) |
|---|---|
| 1 lb | 0.0714285714 st |
| 5 lb | 0.3571428571 st |
| 10 lb | 0.7142857143 st |
| 25 lb | 1.785714286 st |
| 50 lb | 3.571428571 st |
| 100 lb | 7.142857143 st |
Reverse conversion: Stone to Pound
0.0714285714 st × 14 = 0.9999999996 lb
0.0714285714 stones = 0.9999999996 pounds.
pounds = stones × 14
For a page dedicated to this direction, see Stone to Pound.
Pound vs. Stone
| Aspect | Pound | Stone |
|---|---|---|
| Family | US/imperial customary unit | UK customary unit |
| Typical use | Body weight and food retail packaging in the United States | Body weight reporting in the UK and Ireland (e.g. '12 stone 5 pounds') |
| Where it's used | United States (primary mass/weight unit) | United Kingdom and Ireland (body weight) |
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 Stone
Stone (st) measures mass. A stone is 14 pounds: exactly 6.35029318 kilograms. It is classified as a UK customary unit.
Where it's used: United Kingdom and Ireland (body weight)
Uses of the Stone today
- Body weight reporting in the UK and Ireland (e.g. '12 stone 5 pounds')
- Historical wool and agricultural produce weighing
History of the Stone
The stone dates to medieval England as a general-purpose weight unit, historically varying by region and commodity (a 'stone' of wool differed from a 'stone' of meat) before settling on 14 pounds for general use. It remains in everyday use for body weight in the UK and Ireland, unlike most other English customary units which have been replaced or supplemented by metric measures.
Historical origin. Stone was not the invention of a single named person; it developed through the process described above.
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.
Stone — sources
- UK Weights and Measures Act 1985 — Confirms the stone (14 lb) as a legally recognized UK unit for body weight.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many stones are in 1 pound?
1 pound equals 0.0714285714 stones, using the exact defined conversion factor rather than an estimate.
How do I convert pound to stone?
Multiply the pound value by 0.07142857143. The converter above does this instantly to whatever precision you set.
How do I convert stone back to pound?
Use the reverse factor: 1 stone equals 14 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 stone?
Stone (st) measures mass. A stone is 14 pounds: exactly 6.35029318 kilograms. It is classified as a UK customary unit.
Is the pound to stone conversion exact?
Yes. A stone is 14 pounds: exactly 6.35029318 kilograms. 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