A stone is 14 pounds.
Stones to Atomic mass units Converter — st to u
Convert Stone (st) to Atomic mass unit (u) using the exact conversion factor (1 stone = 3.824236e+27 atomic mass unit). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Stones to Atomic mass units 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.
The unified atomic mass unit is used in atomic physics.
Result = input x 6.35029318 / 1.66053907e-27.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Stones to Atomic mass units
Weight conversions between Stone and Atomic mass unit 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. Stone is typically associated with united Kingdom and Ireland (body weight), while Atomic mass unit is typically associated with used internationally in chemistry and physics, not a general-public unit.
Formula
atomic mass units = stones × 3.824236e+27
This factor comes from each unit's defined relationship to the category's base unit: 1 stone equals 6.35029318 base units, and 1 atomic mass unit equals 1.660539e-27 base units, so dividing one by the other gives the direct stone-to-atomic mass unit factor of 3.824236e+27.
Simple example
1 st × 3.824236e+27 = 3.824236e+27 u
1 stone = 3.824236e+27 atomic mass units.
Real-world example
50 st × 3.824236e+27 = 1.912118e+29 u
50 stones = 1.912118e+29 atomic mass units.
Conversion table
| Stone (st) | Atomic mass unit (u) |
|---|---|
| 1 st | 3.824236e+27 u |
| 5 st | 1.912118e+28 u |
| 10 st | 3.824236e+28 u |
| 25 st | 9.56059e+28 u |
| 50 st | 1.912118e+29 u |
| 100 st | 3.824236e+29 u |
Reverse conversion: Atomic mass unit to Stone
3.824236e+27 u × 2.614901e-28 = 1.000000015 st
3.824236e+27 atomic mass units = 1.000000015 stones.
stones = atomic mass units × 2.614901e-28
For a page dedicated to this direction, see Atomic mass unit to Stone.
Stone vs. Atomic mass unit
| Aspect | Stone | Atomic mass unit |
|---|---|---|
| Family | UK customary unit | Non-SI unit accepted for use with SI (scientific) |
| Typical use | Body weight reporting in the UK and Ireland (e.g. '12 stone 5 pounds') | Expressing atomic and molecular masses in chemistry |
| Where it's used | United Kingdom and Ireland (body weight) | Used internationally in chemistry and physics, not a general-public unit |
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.
Understanding the Atomic mass unit
Atomic mass unit (u) measures mass. The unified atomic mass unit is defined as exactly 1/12 the mass of a carbon-12 atom, approximately 1.6605390666 × 10⁻²⁷ kg. It is classified as a Non-SI unit accepted for use with SI (scientific).
Where it's used: Used internationally in chemistry and physics, not a general-public unit
Uses of the Atomic mass unit today
- Expressing atomic and molecular masses in chemistry
- Nuclear and particle physics mass calculations
- Molecular weight tables and mass spectrometry
History of the Atomic mass unit
Atomic mass scales existed before international standardization, using either oxygen-16 or natural oxygen as a reference. In 1961, the International Union of Pure and Applied Chemistry (IUPAC) and physicists agreed on a unified scale based on carbon-12, ending decades of divergent chemistry and physics mass scales.
The unified atomic mass unit (u), also called the dalton (Da) in SI-adjacent contexts, is now tied to the carbon-12 standard and remains the base unit for atomic and molecular mass tables used across chemistry and physics.
Historical origin. Atomic mass unit was not the invention of a single named person; it developed through the process described above.
Stone — sources
- UK Weights and Measures Act 1985 — Confirms the stone (14 lb) as a legally recognized UK unit for body weight.
Atomic mass unit — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the unified atomic mass unit and its carbon-12 definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many atomic mass units are in 1 stone?
1 stone equals 3.824236e+27 atomic mass units, using the exact defined conversion factor rather than an estimate.
How do I convert stone to atomic mass unit?
Multiply the stone value by 3.824236e+27. The converter above does this instantly to whatever precision you set.
How do I convert atomic mass unit back to stone?
Use the reverse factor: 1 atomic mass unit equals 2.614901e-28 stones. You can also use the swap control in the converter above to flip the direction instantly.
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.
What is a atomic mass unit?
Atomic mass unit (u) measures mass. The unified atomic mass unit is defined as exactly 1/12 the mass of a carbon-12 atom, approximately 1.6605390666 × 10⁻²⁷ kg. It is classified as a Non-SI unit accepted for use with SI (scientific).
Is the stone to atomic mass unit conversion exact?
Yes. The unified atomic mass unit is defined as exactly 1/12 the mass of a carbon-12 atom, approximately 1.6605390666 × 10⁻²⁷ kg. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the stone still used today?
United Kingdom and Ireland (body weight)