Ounces to Milligrams Converter
Convert ounces to milligrams — one avoirdupois ounce is exactly 28,349.523125 mg. Results update as you type; exact factors shown.
One ounce is 28,349.5231 milligrams — see the exact factor, not a rounded rule of thumb.
How the ounces to milligrams converter works
Mass converts through the kilogram. The avoirdupois pound has been exactly 0.45359237 kg since 1959, so an ounce is 28.349523125 g and a stone (14 lb) is 6.35029318 kg. A US short ton is 2,000 lb; an imperial long ton is 2,240 lb; a metric tonne is 1,000 kg.
Australia is fully metric under the National Measurement Act 1960; imperial units appear only in trade with the US and in older documents.
Common mass conversions
| From | To | Units |
|---|---|---|
| 0.01 oz | 283.4952 mg | ounces to milligrams |
| 0.1 oz | 2,834.9523 mg | ounces to milligrams |
| 0.25 oz | 7,087.3808 mg | ounces to milligrams |
| 0.5 oz | 14,174.7616 mg | ounces to milligrams |
| 1 oz | 28,349.5231 mg | ounce to milligrams |
| 2 oz | 56,699.0463 mg | ounces to milligrams |
| 4 oz | 113,398.0925 mg | ounces to milligrams |
| 8 oz | 226,796.185 mg | ounces to milligrams |
| 12 oz | 340,194.2775 mg | ounces to milligrams |
| 16 oz | 453,592.37 mg | ounces to milligrams |
| 32 oz | 907,184.74 mg | ounces to milligrams |
| 100 oz | 2,834,952.3125 mg | ounces to milligrams |
Units in this converter and their exact factors
| Unit | Symbol | One unit in kilograms |
|---|---|---|
| milligram | mg | 0.000001 kilogram |
| gram | g | 0.001 kilogram |
| kilogram | kg | 1 kilogram |
| tonne (metric ton) | t | 1,000 kilogram |
| ounce | oz | 0.0283495231 kilogram |
| pound | lb | 0.45359237 kilogram |
| stone | st | 6.35029318 kilogram |
| US ton (short) | US ton | 907.18474 kilogram |
| imperial ton (long) | long ton | 1,016.0469088 kilogram |
FAQFrequently asked questions about mass conversion
How many milligrams in an ounce?
Exactly 28,349.523125, because the pound is defined as exactly 0.45359237 kg.
What is 1 oz in grams?
28.35 g.
Why would I need milligrams?
Dosage, analytical work and small-quantity trade where a gram is too coarse.
Is a troy ounce different?
Yes — 31,103.5 mg, about 10% heavier. It is used for precious metals only.
What is 16 oz?
One pound, or 453,592 mg.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Measurement Institute (NMI) — Australia's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.