Convert Ounce to Milligram (oz → mg)

Converting ounces to milligrams 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 28,349.523

   The conversion factor from oz to mg is 28,349.523. Multiply your value by this number.
3. 3
   Read the result in milligrams

   The result is your value in milligrams (mg).

Multiply the value in ounces by 28,349.523. For the reverse direction, multiply by 0.00003527.

• ✓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 Milligram?

The milligram equals one thousandth of a gram (0.001 g) or 10⁻⁶ kilograms, and is the standard unit for pharmaceutical dosing, vitamin labeling, food additives, and chemistry laboratory work. A typical aspirin tablet contains 325–500 mg of active ingredient, and recommended daily vitamin C intake is around 75–90 mg. The milligram is essential in toxicology (LD50 values are often given in mg per kg of body weight), water-quality testing (dissolved minerals in mg/L), and trace-element analysis. It relates to the gram (1,000 mg = 1 g), the microgram (1,000 µg = 1 mg), and the grain (1 grain ≈ 64.8 mg). Pharmaceutical prescriptions worldwide rely on milligrams, and accurate sub-milligram balances are standard in research and pharmacy environments.

• Prescription and over-the-counter drug dosing
• Vitamin and mineral supplement labelling
• Trace element analysis in laboratories