Convert ounces to milligrams
Converting ounces to milligrams is a common weight task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 oz equals 28,349.5 mg, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert ounces to milligrams
To convert ounces to milligrams, multiply the number of ounces by 28,349.5. For example, 10 oz × 28,349.5 = 283,495 mg.
mg = oz × 28,349.5
- Write down the value in ounces you want to convert.
- Multiply it by 28,349.5 (the exact oz→mg factor).
- The result is your value in milligrams. Check it below with the converter or the table.
Conversion table
Common values of ounces and their equivalents in milligrams:
| oz | mg |
|---|---|
| 1 | 28,349.5 |
| 2 | 56,699 |
| 3 | 85,048.6 |
| 4 | 113,398 |
| 5 | 141,748 |
| 10 | 283,495 |
| 20 | 566,990 |
| 25 | 708,738 |
| 50 | 1,417,480 |
| 100 | 2,834,950 |
| 250 | 7,087,380 |
| 500 | 14,174,800 |
About these units
Ounce (oz). The avoirdupois ounce is a US customary unit defined as exactly 28.349523125 grams, or 1/16 of a pound. Food portions and packaged goods in the US are labeled in ounces.
Milligram (mg). A milligram is one thousandth of a gram, used for medication doses, vitamins and chemical additives. Precision at this scale matters in pharmacology and nutrition labeling.
Frequently asked questions
How do I convert ounces to milligrams?
To convert ounces to milligrams, multiply the number of ounces by 28,349.5. For example, 10 oz × 28,349.5 = 283,495 mg. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many milligrams are in 1 ounce?
1 oz = 28,349.5 mg. That is the fixed relationship used by this converter and by international standards.
How many ounces are in 1 milligram?
1 mg = 0.000035274 oz. If you are converting in the opposite direction, use our Milligram to Ounce converter for the dedicated table and FAQ.
Is the ounces to milligrams conversion exact?
Yes. Both units are defined by international agreement, so the factor of 28,349.5 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is ounce used for?
The avoirdupois ounce is a US customary unit defined as exactly 28.349523125 grams, or 1/16 of a pound. Food portions and packaged goods in the US are labeled in ounces.