Weight Converter
Conversion Formula
Grams to Grains Formula
To convert between grams and grains, use these formulas:
Grains to Grams Formula
Enter a value in either field above to see the conversion result in the other field.
Common Conversions
| Grams | Grains |
|---|---|
| 1 g | 15.432 gr |
| 5 g | 77.162 gr |
| 10 g | 154.324 gr |
| 50 g | 771.618 gr |
| 100 g | 1543.236 gr |
| 500 g | 7716.179 gr |
About Weight Units
The gram (g) is a metric unit of weight defined as one thousandth of a kilogram. It's widely used in scientific contexts and in most countries worldwide.
The grain (gr) is a unit of weight equal to 64.79891 milligrams. It is one of the earliest units of mass and is the smallest unit in the troy, avoirdupois, and apothecaries' systems.
Practical Applications
Converting between grams and grains is essential for:
- Ammunition and reloading measurements
- Jewelry and precious metals weighing
- Pharmaceutical dosage calculations
- Historical weight measurements
- Scientific research and precision measurements
About Grains
Typical Use Cases
The grain is predominantly used in ammunition manufacturing and reloading, where bullet weights are universally specified in grains (e.g., a 9mm bullet might be 115 grains or 147 grains). It's also employed in pharmacy for measuring active pharmaceutical ingredients, in archery for arrow weights, and occasionally in jewelry for small gemstones. Handloaders and competitive shooters rely heavily on grain measurements for precise powder charges and projectile weights.
Historical Background
The grain is one of humanity's oldest units of measurement, originally based on the weight of a single grain of barley. It predates the metric system by millennia and was standardized across the troy, avoirdupois, and apothecaries' weight systems. Defined as exactly 64.79891 milligrams since 1959, the grain remains in use primarily because of its deep entrenchment in firearms and pharmaceutical traditions, where changing to metric would require massive industry-wide adjustments.
Conversion Tips
When converting grams to grains for ammunition, note that even small differences matter: a 0.1-gram change equals about 1.5 grains, which can affect ballistics. For powder charges in reloading, always double-check conversions, as incorrect measurements can be dangerous. A useful reference: 1 gram ≈ 15.43 grains, so 7 grams of gunpowder ≈ 108 grains. Always use precision scales and verify measurements independently when working with propellants or pharmaceuticals.
Frequently Asked Questions
How many grains are in a gram?
One gram equals 15.4324 grains. This conversion is essential for ammunition reloading and pharmaceutical measurements.
Why do bullets use grains instead of grams?
The firearms industry has used grains for centuries as a traditional measurement. Bullet weights are universally specified in grains (e.g., 55-grain, 124-grain) across all ammunition manufacturers worldwide.
Is this converter accurate for reloading ammunition?
Yes, our converter is accurate to 3 decimal places, suitable for most reloading applications. However, always use a precision reloading scale for actual powder charges, as safety is critical.
Are grains the same in pharmacy and ammunition?
Yes, the grain is standardized at exactly 64.79891 milligrams regardless of industry. However, pharmaceutical use of grains is declining in favor of metric measurements.
What is the practical difference between grains and carats for gemstones?
While both units measure small weights, grains and carats serve different industries. One carat equals exactly 200 milligrams or approximately 3.086 grains, making carats slightly larger. Gemologists universally use carats for diamond and precious stone weight, whereas grains are reserved for pearls and gunpowder in specialized contexts. If you're purchasing a 1-carat diamond, it weighs about 3.1 grains. For ammunition reloading or pharmaceutical compounding, grains remain the standard due to historical precision scales calibrated in this unit. Understanding this distinction prevents confusion when working across jewelry appraisal and ballistics fields.
About Our Conversion Standards
Our weight conversions are based on the International System of Units (SI) and standards published by the National Institute of Standards and Technology (NIST). All conversion factors are accurate to at least 6 decimal places, ensuring precision for both everyday and professional use.
Data Sources: NIST Handbook 44, International Bureau of Weights and Measures (BIPM), ISO 80000-3:2006
Last Verified: October 2025