The unified atomic mass unit is used in atomic physics.
Atomic mass units to Attograms Converter — u to ag
Convert Atomic mass unit (u) to Attogram (ag) using the exact conversion factor (1 atomic mass unit = 0.0000016605 attogram). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Atomic mass units to Attograms 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.
Attogram is 1e-18 gram units.
Result = input x 1.66053907e-27 / 1e-21.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Atomic mass units to Attograms
Weight conversions between Atomic mass unit and Attogram 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 Attogram is typically associated with used in specialized scientific measurement, not everyday contexts.
Formula
attograms = atomic mass units × 0.0000016605390666
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 attogram equals 1e-21 base units, so dividing one by the other gives the direct atomic mass unit-to-attogram factor of 0.0000016605390666.
Simple example
1 u × 0.000001660539067 = 0.0000016605 ag
1 atomic mass unit = 0.0000016605 attograms.
Real-world example
50 u × 0.000001660539067 = 0.000083027 ag
50 atomic mass units = 0.000083027 attograms.
Conversion table
| Atomic mass unit (u) | Attogram (ag) |
|---|---|
| 1 u | 0.0000016605 ag |
| 5 u | 0.0000083027 ag |
| 10 u | 0.0000166054 ag |
| 25 u | 0.0000415135 ag |
| 50 u | 0.000083027 ag |
| 100 u | 0.0001660539 ag |
Reverse conversion: Attogram to Atomic mass unit
0.0000016605 ag × 602214.0762 = 0.9999764735 u
0.0000016605 attograms = 0.9999764735 atomic mass units.
atomic mass units = attograms × 602214.076208
For a page dedicated to this direction, see Attogram to Atomic mass unit.
Atomic mass unit vs. Attogram
| Aspect | Atomic mass unit | Attogram |
|---|---|---|
| Family | Non-SI unit accepted for use with SI (scientific) | SI derived (metric prefix) unit |
| Typical use | Expressing atomic and molecular masses in chemistry | Nanotechnology and single-molecule mass measurement |
| Where it's used | Used internationally in chemistry and physics, not a general-public unit | Used in specialized scientific measurement, not everyday contexts |
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 Attogram
Attogram (ag) measures mass. An attogram is 10⁻¹⁸ grams (10⁻²¹ kilograms) — 'atto-' is the SI prefix for one quintillionth. It is classified as a SI derived (metric prefix) unit.
Where it's used: Used in specialized scientific measurement, not everyday contexts
Uses of the Attogram today
- Nanotechnology and single-molecule mass measurement
- Analytical chemistry at extremely small mass scales
- Comparing against atomic-scale mass units like the atomic mass unit
History of the Attogram
The attogram is simply the gram combined with the SI prefix 'atto-' (10⁻¹⁸), one of the small-scale metric prefixes introduced by the International Committee for Weights and Measures as part of the broader SI prefix system, not a unit with its own separate history.
Historical origin. Attogram 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.
Attogram — sources
- BIPM SI Brochure — SI prefixes — Defines 'atto-' as the prefix for 10⁻¹⁸.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many attograms are in 1 atomic mass unit?
1 atomic mass unit equals 0.0000016605 attograms, using the exact defined conversion factor rather than an estimate.
How do I convert atomic mass unit to attogram?
Multiply the atomic mass unit value by 0.000001660539067. The converter above does this instantly to whatever precision you set.
How do I convert attogram back to atomic mass unit?
Use the reverse factor: 1 attogram equals 602,214.0762 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 attogram?
Attogram (ag) measures mass. An attogram is 10⁻¹⁸ grams (10⁻²¹ kilograms) — 'atto-' is the SI prefix for one quintillionth. It is classified as a SI derived (metric prefix) unit.
Is the atomic mass unit to attogram 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