Grain to Atomic Mass Unit Converter
Convert Grain (gr) to Atomic Mass Unit (u) instantly. 1 gr = 3.902282e+22 u.
Mass Converter
26 units available
1 gr = 3.902282e+22 u
Formula:
u = gr × 3.902282e+22With your value: 1 gr = 3.902282e+22 u
How big is that?
Everyday references on a logarithmic scale, all expressed in grain so you can sanity-check the result.
Other Grain to Atomic Mass Unit conversions
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 |
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 |
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.
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
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
How to Convert Grain to Atomic Mass Unit
To convert from Grain (gr) to Atomic Mass Unit (u), multiply the value by 3.902282e+22.
Formula: u = gr × 3.902282e+22
Reverse: gr = u × 2.562603e-23
Step-by-Step Example
- Start with your value in Grain. For example: 5 gr
- Multiply by the conversion factor: 5 x 3.902282e+22
- The result is: 1.951141e+23 u
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).
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.
Frequently Asked Questions
How many Atomic Mass Unit are in 1 Grain?
There are exactly 3.902282e+22 Atomic Mass Unit in 1 Grain. This means the conversion factor from Grain to Atomic Mass Unit is 3.902282e+22.
What is the formula to convert Grain to Atomic Mass Unit?
The formula to convert Grain to Atomic Mass Unit is: u = gr × 3.902282e+22. For example, to convert 10 Grain to Atomic Mass Unit, you would multiply 10 by 3.902282e+22.
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 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 are the common uses of Grain?
The Grain is commonly used in ammunition, archery, pharmacy (historic).
Related Mass Conversions
Cite this page
UnitConvertLab. (2026). Grain to Atomic Mass Unit converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/grain-to-atomic_mass_unit