A grain is exactly 64.79891 milligrams.
Grains to Milligrams Converter — gr to mg
Convert Grain (gr) to Milligram (mg) using the exact conversion factor (1 grain = 64.79891 milligram). See the formula, worked examples, and conversion table.
Grains to Milligrams converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
Milligram is 0.001 gram units.
Result = input x 6.479891e-5 / 1e-6.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Grains to Milligrams
Weight conversions between Grain and Milligram come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Specifically: A grain is exactly 64.79891 milligrams, and milligram is 0.001 gram units.
Formula
milligrams = grains × 64.79891
This factor comes from each unit's defined relationship to the category's base unit: 1 grain equals 0.00006479891 base units, and 1 milligram equals 0.000001 base units, so dividing one by the other gives the direct grain-to-milligram factor of 64.79891.
Simple example
1 gr × 64.79891 = 64.79891 mg
1 grain = 64.79891 milligrams.
Real-world example
50 gr × 64.79891 = 3,239.9455 mg
50 grains = 3,239.9455 milligrams.
Conversion table
| Grain (gr) | Milligram (mg) |
|---|---|
| 1 gr | 64.79891 mg |
| 5 gr | 323.99455 mg |
| 10 gr | 647.9891 mg |
| 25 gr | 1,619.97275 mg |
| 50 gr | 3,239.9455 mg |
| 100 gr | 6,479.891 mg |
Reverse conversion: Milligram to Grain
64.79891 mg × 0.01543235835 = 1 gr
64.79891 milligrams = 1 grains.
grains = milligrams × 0.0154323583529
For a page dedicated to this direction, see Milligram to Grain.
Understanding the Grain (gr)
A grain is exactly 64.79891 milligrams.
Understanding the Milligram (mg)
Milligram is 0.001 gram units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milligrams are in 1 grain?
1 grain equals 64.79891 milligrams, using the exact defined conversion factor rather than an estimate.
How do I convert grain to milligram?
Multiply the grain value by 64.79891. The converter above does this instantly to whatever precision you set.
How do I convert milligram back to grain?
Use the reverse factor: 1 milligram equals 0.0154323584 grains. You can also use the swap control in the converter above to flip the direction instantly.
What is a grain?
Grain (gr) is a unit of mass/weight.
What is a milligram?
Milligram (mg) is a unit of mass/weight.
Is the grain to milligram conversion exact?
Yes. Both grain and milligram are defined by fixed standards rather than physical artifacts, so the factor of 64.79891 used above is exact to as many digits as you choose to display.