The unified atomic mass unit is used in atomic physics.
Atomic mass units to Stones Converter — u to st
Convert Atomic mass unit (u) to Stone (st) using the exact conversion factor (1 atomic mass unit = 2.614901e-28 stone). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Atomic mass units 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 1.66053907e-27 / 6.35029318.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Atomic mass units to Stones
Weight conversions between Atomic mass unit 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. Atomic mass unit is typically associated with used internationally in chemistry and physics, not a general-public unit, while Stone is typically associated with united Kingdom and Ireland (body weight).
Formula
stones = atomic mass units × 2.614901e-28
This factor comes from each unit's defined relationship to the category's base unit: 1 atomic mass unit equals 1.660539e-27 base units, and 1 stone equals 6.35029318 base units, so dividing one by the other gives the direct atomic mass unit-to-stone factor of 2.614901e-28.
Simple example
1 u × 2.614901e-28 = 2.614901e-28 st
1 atomic mass unit = 2.614901e-28 stones.
Real-world example
50 u × 2.614901e-28 = 1.307451e-26 st
50 atomic mass units = 1.307451e-26 stones.
Conversion table
| Atomic mass unit (u) | Stone (st) |
|---|---|
| 1 u | 2.614901e-28 st |
| 5 u | 1.307451e-27 st |
| 10 u | 2.614901e-27 st |
| 25 u | 6.537254e-27 st |
| 50 u | 1.307451e-26 st |
| 100 u | 2.614901e-26 st |
Reverse conversion: Stone to Atomic mass unit
2.614901e-28 st × 3.824236e+27 = 0.9999998386 u
2.614901e-28 stones = 0.9999998386 atomic mass units.
atomic mass units = stones × 3.824236e+27
For a page dedicated to this direction, see Stone to Atomic mass unit.
Atomic mass unit vs. Stone
| Aspect | Atomic mass unit | Stone |
|---|---|---|
| Family | Non-SI unit accepted for use with SI (scientific) | UK customary unit |
| Typical use | Expressing atomic and molecular masses in chemistry | Body weight reporting in the UK and Ireland (e.g. '12 stone 5 pounds') |
| Where it's used | Used internationally in chemistry and physics, not a general-public unit | United Kingdom and Ireland (body weight) |
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.
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.
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.
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 atomic mass unit?
1 atomic mass unit equals 2.614901e-28 stones, using the exact defined conversion factor rather than an estimate.
How do I convert atomic mass unit to stone?
Multiply the atomic mass unit value by 2.614901e-28. The converter above does this instantly to whatever precision you set.
How do I convert stone back to atomic mass unit?
Use the reverse factor: 1 stone equals 3.824236e+27 atomic mass units. You can also use the swap control in the converter above to flip the direction instantly.
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).
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 atomic mass unit 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.
Where is the atomic mass unit still used today?
Used internationally in chemistry and physics, not a general-public unit