Atomic Mass Unit to Grain Converter
Convert Atomic Mass Unit (u) to Grain (gr) instantly. 1 u = 2.562603e-23 gr.
Mass Converter
26 units available
1 u = 2.562603e-23 gr
Formula:
gr = u × 2.562603e-23With your value: 1 u = 2.562603e-23 gr
How big is that?
Everyday references on a logarithmic scale, all expressed in atomic mass unit so you can sanity-check the result.
Other Atomic Mass Unit to Grain conversions
Atomic Mass Unit to Grain Conversion Table
| Atomic Mass Unit (u) | Grain (gr) |
|---|---|
| 0.5 | 1.281302e-23 |
| 1 | 2.562603e-23 |
| 2 | 5.125207e-23 |
| 5 | 1.281302e-22 |
| 10 | 2.562603e-22 |
| 15 | 3.843905e-22 |
| 20 | 5.125207e-22 |
| 25 | 6.406508e-22 |
| 50 | 1.281302e-21 |
| 100 | 2.562603e-21 |
| 250 | 6.406508e-21 |
| 500 | 1.281302e-20 |
| 1000 | 2.562603e-20 |
Grain to Atomic Mass Unit Conversion Table
| Grain (gr) | Atomic Mass Unit (u) |
|---|---|
| 0.5 | 1.951141e+22 |
| 1 | 3.902282e+22 |
| 2 | 7.804563e+22 |
| 5 | 1.951141e+23 |
| 10 | 3.902282e+23 |
| 15 | 5.853422e+23 |
| 20 | 7.804563e+23 |
| 25 | 9.755704e+23 |
| 50 | 1.951141e+24 |
| 100 | 3.902282e+24 |
| 250 | 9.755704e+24 |
| 500 | 1.951141e+25 |
| 1000 | 3.902282e+25 |
Where these values come from
Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.
Atomic Mass Unit (u)
Mass
The unified atomic mass unit is 1/12 the mass of a free carbon-12 atom: 1.660 539 068 92(52) × 10⁻²⁷ kg.
Experimentally determined; the last digits carry the CODATA 2022 uncertainty.
Source: CODATA Internationally Recommended Values of the Fundamental Physical Constants (2022 adjustment)
CODATA / NIST · Reviewed 2026-07-01
Grain (gr)
Mass
Traceable to the kilogram, defined by fixing the Planck constant at 6.626 070 15 × 10⁻³⁴ J·s. Avoirdupois masses derive from the 1959 international pound (0.453 592 37 kg exactly).
Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)
Bureau International des Poids et Mesures · Reviewed 2026-07-01
How to Convert Atomic Mass Unit to Grain
To convert from Atomic Mass Unit (u) to Grain (gr), multiply the value by 2.562603e-23.
Formula: gr = u × 2.562603e-23
Reverse: u = gr × 3.902282e+22
Step-by-Step Example
- Start with your value in Atomic Mass Unit. For example: 5 u
- Multiply by the conversion factor: 5 x 2.562603e-23
- The result is: 1.281302e-22 gr
About Atomic Mass Unit
The unified atomic mass unit (dalton) is 1/12 the mass of a carbon-12 atom, about 1.66054×10⁻²⁷ kg.
Common uses: chemistry, mass spectrometry, molecular biology.
About Grain
The grain equals exactly 64.79891 milligrams and was originally the weight of a single barleycorn. It is still the standard unit for bullets, propellant and arrows.
Common uses: ammunition, archery, pharmacy (historic).
Frequently Asked Questions
How many Grain are in 1 Atomic Mass Unit?
There are exactly 2.562603e-23 Grain in 1 Atomic Mass Unit. This means the conversion factor from Atomic Mass Unit to Grain is 2.562603e-23.
What is the formula to convert Atomic Mass Unit to Grain?
The formula to convert Atomic Mass Unit to Grain is: gr = u × 2.562603e-23. For example, to convert 10 Atomic Mass Unit to Grain, you would multiply 10 by 2.562603e-23.
What is a Atomic Mass Unit?
The unified atomic mass unit (dalton) is 1/12 the mass of a carbon-12 atom, about 1.66054×10⁻²⁷ kg.
What is a Grain?
The grain equals exactly 64.79891 milligrams and was originally the weight of a single barleycorn. It is still the standard unit for bullets, propellant and arrows.
What are the common uses of Atomic Mass Unit?
The Atomic Mass Unit is commonly used in chemistry, mass spectrometry, molecular biology.
Related Mass Conversions
Cite this page
UnitConvertLab. (2026). Atomic Mass Unit to Grain converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/atomic_mass_unit-to-grain