Convert Ounce to Grain (oz → gr)

Converting ounces to grains is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in ounces

   Start with the number of ounces (oz) you want to convert.
2. 2
   Multiply by 437.5

   The conversion factor from oz to gr is 437.5. Multiply your value by this number.
3. 3
   Read the result in grains

   The result is your value in grains (gr).

Multiply the value in ounces by 437.5. For the reverse direction, multiply by 0.002286.

• ✓1 oz = 28.35 g exactly (avoirdupois); 1 troy oz = 31.10 g.
• ✓16 oz = 1 lb in the avoirdupois system used for food.
• ✓When converting a US recipe, 1 oz ≈ 2 tablespoons of a liquid ingredient.

• ✗Confusing mass ounces (28.35 g) with fluid ounces (volume).
• ✗Using avoirdupois ounces (28.35 g) for precious-metal pricing — gold is in troy ounces (31.10 g).
• ✗Multiplying lb × 16 and calling the result oz — correct only for weight, not volume.

What is the Ounce?

The ounce equals exactly 28.349523125 grams or 1/16 of a pound. The word derives from the Latin 'uncia,' meaning one twelfth (the original Roman ounce was 1/12 of a Roman pound). The modern avoirdupois ounce, used for everyday weights in the United States and the United Kingdom, replaced the older Tower and Troy systems. It is the standard unit for American kitchen recipes (where 'ounce' refers to weight, distinct from the fluid ounce of volume), postal rates, package sizes (a 12-oz can of soda), and boxing-glove weights. Precious metals like gold and silver use the troy ounce (31.103 g), about 10% heavier than the avoirdupois ounce. The ounce relates to the pound (16 oz = 1 lb), the gram (1 oz ≈ 28.35 g), and the grain (1 oz = 437.5 grains).

• American and British cooking recipes
• Food packaging in the US
• Precious metals (troy ounce = 31.10 g, different from avoirdupois)

What is the Grain?

The grain equals exactly 64.79891 milligrams (0.06479891 g) and is the smallest unit in the traditional avoirdupois weight system. Originally based on the average mass of a single grain of wheat or barley, the unit was standardized to its current value with the 1959 international yard and pound agreement. The grain is still used in pharmaceutical compounding (some older drug formulations specify grains, especially aspirin and codeine), arrow tips and ammunition (bullet weights are commonly given in grains — a 9 mm bullet is around 115 grains), and precious-metal weighing (one troy ounce = 480 grains). It relates to the ounce (437.5 grains = 1 oz avoirdupois), the pound (7,000 grains = 1 lb), and the milligram (1 grain ≈ 64.8 mg). The unit reflects medieval agriculture's role in shaping early measurement systems.

• Bullet and gunpowder mass in ballistics
• Older pharmaceutical dosing in Anglo-Saxon countries
• Arrow shaft and archery equipment weights