Grain to Milligram Converter
Convert Grain (gr) to Milligram (mg) instantly. 1 gr = 64.79891 mg.
Mass Converter
26 units available
1 gr = 64.79891 mg
Formula:
mg = gr × 64.79891With your value: 1 gr = 64.79891 mg
How big is that?
Everyday references on a logarithmic scale, all expressed in grain so you can sanity-check the result.
Other Grain to Milligram conversions
Grain to Milligram Conversion Table
| Grain (gr) | Milligram (mg) |
|---|---|
| 0.5 | 32.399455 |
| 1 | 64.79891 |
| 2 | 129.59782 |
| 5 | 323.99455 |
| 10 | 647.9891 |
| 15 | 971.98365 |
| 20 | 1,295.9782 |
| 25 | 1,619.97275 |
| 50 | 3,239.9455 |
| 100 | 6,479.891 |
| 250 | 16,199.7275 |
| 500 | 32,399.455 |
| 1000 | 64,798.91 |
Milligram to Grain Conversion Table
| Milligram (mg) | Grain (gr) |
|---|---|
| 0.5 | 0.007716 |
| 1 | 0.015432 |
| 2 | 0.030865 |
| 5 | 0.077162 |
| 10 | 0.154324 |
| 15 | 0.231485 |
| 20 | 0.308647 |
| 25 | 0.385809 |
| 50 | 0.771618 |
| 100 | 1.543236 |
| 250 | 3.85809 |
| 500 | 7.716179 |
| 1000 | 15.432358 |
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
Milligram (mg)
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 Grain to Milligram
To convert from Grain (gr) to Milligram (mg), multiply the value by 64.79891.
Formula: mg = gr × 64.79891
Reverse: gr = mg × 0.0154323584
Step-by-Step Example
- Start with your value in Grain. For example: 5 gr
- Multiply by the conversion factor: 5 x 64.79891
- The result is: 323.99455 mg
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 Milligram
The milligram equals one thousandth of a gram and is the standard unit for drug dosage and nutrient quantities.
Common uses: medication dosage, nutrition labels, laboratory work.
Frequently Asked Questions
How many Milligram are in 1 Grain?
There are exactly 64.79891 Milligram in 1 Grain. This means the conversion factor from Grain to Milligram is 64.79891.
What is the formula to convert Grain to Milligram?
The formula to convert Grain to Milligram is: mg = gr × 64.79891. For example, to convert 10 Grain to Milligram, you would multiply 10 by 64.79891.
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 Milligram?
The milligram equals one thousandth of a gram and is the standard unit for drug dosage and nutrient quantities.
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 Milligram converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/grain-to-milligram