Convert Grains to Micrograms
Convert Grains (gr) to Micrograms (µg) instantly and accurately.
Conversion Formula
µg = gr × 64798.91
About Grains
A grain (gr) is the smallest unit in both the avoirdupois and troy weight systems, equal to exactly 64.79891 milligrams. Originally defined as the mass of a single grain of barley or wheat from the middle of an ear, it has been a standard of weight since ancient times. Today, grains are used to weigh gunpowder charges and bullets (a standard .308 rifle bullet weighs 168 gr), pharmaceutical preparations in apothecary compounding, and the fineness of gold alloys. Arrowhead and fishing hook weights are also specified in grains.
About Micrograms
A microgram (µg or mcg) is one millionth of a gram (10⁻⁶ g). It is the standard dosing unit for potent medications and micronutrients: vitamin B12 recommended daily intake is 2.4 µg, folic acid supplements are 400 µg, and levothyroxine (thyroid medication) doses are typically 25-200 µg. Air quality standards measure fine particulate matter (PM2.5) in micrograms per cubic meter - the WHO guideline is 15 µg/m³ annual mean. A grain of sand weighs about 50-100 micrograms, and a single snowflake approximately 3 micrograms.
Quick Reference Table
| Grains (gr) | Micrograms (µg) |
|---|---|
| 1 gr | 64798.9 µg |
| 2 gr | 129598 µg |
| 5 gr | 323995 µg |
| 10 gr | 647989 µg |
| 25 gr | 1619970 µg |
| 50 gr | 3239950 µg |
| 100 gr | 6479890 µg |