The unified atomic mass unit is used in atomic physics.
Atomic mass units to Long tons Converter — u to long ton
Convert Atomic mass unit (u) to Long ton (long ton) using the exact conversion factor (1 atomic mass unit = 1.634313e-30 long ton). See the formula, worked examples, conversion table, history, and common uses.
Atomic mass units to Long tons 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 British long ton is 2,240 pounds.
Result = input x 1.66053907e-27 / 1016.046909.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Atomic mass units to Long tons
Weight conversions between Atomic mass unit and Long ton 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 most often used for expressing atomic and molecular masses in chemistry.
Formula
long tons = atomic mass units × 1.634313e-30
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 long ton equals 1016.0469088 base units, so dividing one by the other gives the direct atomic mass unit-to-long ton factor of 1.634313e-30.
Simple example
1 u × 1.634313e-30 = 1.634313e-30 long ton
1 atomic mass unit = 1.634313e-30 long tons.
Real-world example
50 u × 1.634313e-30 = 8.171567e-29 long ton
50 atomic mass units = 8.171567e-29 long tons.
Conversion table
| Atomic mass unit (u) | Long ton (long ton) |
|---|---|
| 1 u | 1.634313e-30 long ton |
| 5 u | 8.171567e-30 long ton |
| 10 u | 1.634313e-29 long ton |
| 25 u | 4.085783e-29 long ton |
| 50 u | 8.171567e-29 long ton |
| 100 u | 1.634313e-28 long ton |
Reverse conversion: Long ton to Atomic mass unit
1.634313e-30 long ton × 6.118778e+29 = 0.9999997622 u
1.634313e-30 long tons = 0.9999997622 atomic mass units.
atomic mass units = long tons × 6.118778e+29
For a page dedicated to this direction, see Long ton to Atomic mass unit.
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 Long ton (long ton)
A British long ton is 2,240 pounds.
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 long tons are in 1 atomic mass unit?
1 atomic mass unit equals 1.634313e-30 long tons, using the exact defined conversion factor rather than an estimate.
How do I convert atomic mass unit to long ton?
Multiply the atomic mass unit value by 1.634313e-30. The converter above does this instantly to whatever precision you set.
How do I convert long ton back to atomic mass unit?
Use the reverse factor: 1 long ton equals 6.118778e+29 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 long ton?
Long ton (long ton) is a unit of mass/weight.
Is the atomic mass unit to long ton 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 atomic mass unit still used today?
Used internationally in chemistry and physics, not a general-public unit