Convert Grain to Atomic Mass Unit
Convert grains to atomic mass unit instantly. 1 grain = 3.902278e+22 atomic mass unit — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Atomic Mass Unit to Grain converter for the reverse conversion.
Units explained
Grain
The grain (gr) equals 1/7000 of an avoirdupois pound, about 64.8 milligrams.
Based on the nominal mass of a single barley grain.
Ammunition and bullet mass, archery, and historical pharmacy.
Standardized through the English avoirdupois system and retained in 1959.
Atomic Mass Unit
One unified atomic mass unit (u) is defined as 1/12 the mass of a carbon-12 atom, about 1.6605E-27 kg.
Introduced to give atomic and molecular masses convenient numerical values.
Atomic, molecular, and nuclear physics and chemistry.
The unified (carbon-12) scale was adopted by IUPAC and IUPAP in 1960-1961.
Grain to Atomic Mass Unit conversion formula
The relationship between grains and atomic mass unit:
To convert grains to atomic mass unit, multiply the value in grains by 3.902278e+22. To reverse, multiply atomic mass unit by 2.562606e-23.
How to use this converter
Type a value into the calculator. The result in atomic mass unit updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Atomic Mass Unit to Grain converter for the reverse direction.
Step-by-step: convert grains to atomic mass unit
- Write down the value in grains (gr).
- Multiply that value by the factor 3.902278e+22.
- The product is the equivalent value in atomic mass unit (u).
- To reverse, multiply the atomic mass unit value by 2.562606e-23.
Worked examples
Example 1 — Convert 1 gr to u:
1 × 3.902278e+22 = 3.902278e+22 u
Example 2 — Convert 100 gr to u:
100 × 3.902278e+22 = 3.902278e+24 u
Real-world example — From microns to sub-micron features
One grain equals one thousand atomic mass unit — the conversion semiconductor designers do constantly when comparing mask feature dimensions to actual transistor gate lengths.
1 gr × 3.902278e+22 = 3.902278e+22 u
Real-world example — Infrared to visible-spectrum mapping
A 10-grain thermal infrared wavelength corresponds to a much larger number in atomic mass unit, the unit favoured for ultraviolet and visible-light specifications.
10 gr × 3.902278e+22 = 3.902278e+23 u
Real-world example — Mid-micron to nanometer
3 grains equals 3,000 atomic mass unit — useful when relating mid-infrared wavelengths (typically quoted in microns) to nanometer-scale visible-light wavelength tables.
3 gr × 3.902278e+22 = 1.170683e+23 u
Grain to Atomic Mass Unit conversion table
Standard reference values for converting grains to atomic mass unit:
| Grain [gr] | Atomic Mass Unit [u] |
|---|---|
| 0.01 | 3.902278e+20 |
| 0.1 | 3.902278e+21 |
| 1 | 3.902278e+22 |
| 2 | 7.804557e+22 |
| 3 | 1.170683e+23 |
| 4 | 1.560911e+23 |
| 5 | 1.951139e+23 |
| 10 | 3.902278e+23 |
| 20 | 7.804557e+23 |
| 30 | 1.170683e+24 |
| 40 | 1.560911e+24 |
| 50 | 1.951139e+24 |
| 100 | 3.902278e+24 |
| 500 | 1.951139e+25 |
| 1000 | 3.902278e+25 |
Frequently asked questions
How many atomic mass unit is 1 grain?
How do I convert grains to atomic mass unit?
How do I convert atomic mass unit back to grains?
How many atomic mass unit is 100 grains?
Popular weight unit conversions
Convert Grain to other weight units
Show all Grain conversions
Metric / SI (18 units)
Avoirdupois (14 units)
Troy & Apothecary (10 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 gr = 3.902278e+22 u) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.