Grains to Milligrams
A grain is about 64.8 milligrams, one of the oldest units of mass, still used for bullet and arrow weights and gunpowder charges. A milligram is one thousandth of a gram, the standard unit for medication dosages on drug labels. 1 gr equals ≈64.7989 mg, so converting between them is a matter of multiplying by that fixed factor — type any value into the converter below and both sides update instantly as you type.
Both units belong to mass, measured here against mass's base unit (kg) — every other mass unit on this site converts through that same reference point, which is why the table below can also be read as a quick cross-check against nearby values.
Formula
mg = gr × ≈64.7989
gr = mg × ≈0.0154324
Worked example: 5 gr × ≈64.7989 = ≈323.995 mg.
Conversion table
| Grain (gr) | Milligram (mg) |
|---|---|
| 1 gr | ≈64.7989 mg |
| 2 gr | ≈129.598 mg |
| 3 gr | ≈194.397 mg |
| 5 gr | ≈323.995 mg |
| 10 gr | ≈647.989 mg |
| 20 gr | ≈1,295.98 mg |
| 25 gr | ≈1,619.97 mg |
| 50 gr | ≈3,239.95 mg |
| 100 gr | ≈6,479.89 mg |
| 250 gr | ≈16,199.7 mg |
| 500 gr | ≈32,399.5 mg |
| 1,000 gr | ≈64,798.9 mg |
Frequently asked
- How many Milligrams in a grain?
- 1 gr equals ≈64.7989 mg.
- How do I convert Grains to Milligrams?
- Multiply the value in gr by ≈64.7989 to get mg. The converter above does this instantly as you type.
- Is the conversion exact?
- Yes — Grain and Milligram are both defined by a fixed conversion factor to mass's base unit (kg), so the result shown is exact to the precision displayed, not an approximation.