The grain conversion selector above selects the mass/weight measurement unit to convert to starting from grains (gr). To make a conversion starting from a unit of mass other than grain, simply click on the "Reset" button.
The grain is a unit of mass in the Imperial and US customary systems of units equal to 0.06479891 × 10-3 kilograms (1 gr = 0.06479891 × 10-3 kg), the base unit of mass in the International System of Units (SI).
One grain (gr) is also equal to 0.06479891 grams (g), or 64.79891 milligrams (mg) or 64,798.91 micrograms (μg) (SI units of mass), or about 1.428571 × 10-4 pounds (lb) or 0.0022857 ounces (oz), which are US customary / Imperial units of mass.
The grain definition varies depending on the system of units used, as follows:
- 1 grain = 1 avoirdupois grain = 1 troy grain = 1 Apothecaries grain = 64.79891 milligrams
- 1 metric grain = 1 pearl grain = 50 milligrams
The grain is commonly used to measure the hardness of water, the mass of gunpowder, smokeless powder and bullets, and occasionally in medical prescriptions.