How to convert ounces to milligrams
To convert ounces to milligrams, multiply by 28,349.523125. Weight and mass conversions matter for cooking, shipping, fitness tracking, medicine and trade.
Ounce to Milligram conversion table
| Ounce (oz) | Milligram (mg) |
|---|---|
| 0.1 oz | 2,834.9523125 mg |
| 0.5 oz | 14,174.7615625 mg |
| 1 oz | 28,349.523125 mg |
| 2 oz | 56,699.04625 mg |
| 3 oz | 85,048.569375 mg |
| 4 oz | 113,398.0925 mg |
| 5 oz | 141,747.615625 mg |
| 10 oz | 283,495.23125 mg |
| 20 oz | 566,990.4625 mg |
| 25 oz | 708,738.078125 mg |
| 50 oz | 1,417,476.15625 mg |
| 100 oz | 2,834,952.3125 mg |
| 500 oz | 14,174,761.5625 mg |
| 1,000 oz | 28,349,523.125 mg |
About the units
Ounce (oz)
An avoirdupois ounce is 1/16 of a pound, exactly 28.349523125 grams, used for food portions and postage.
Milligram (mg)
A milligram is one thousandth of a gram, typically used for medication doses and nutrition labels.
How to use this converter
- Type the number of ounces (oz) in the input box.
- The result in milligrams appears instantly — no button needed.
- See the same value in every other weight unit just below.
- Use “Swap units” to convert milligrams back to ounces.
When you’ll use the ounce to milligram conversion
Converting ounces to milligrams comes up more often than you might expect — for example when following a recipe written in grams, checking luggage against an airline limit, or tracking body weight in a different unit. Type your number once and you get the exact answer plus every related unit, so you don’t need to convert twice.
💡 For a quick estimate in your head, multiply by about 28,000 (the exact factor is 28,349.523125).
Watch out for these mix-ups
- Mixing the avoirdupois ounce with the fluid ounce (volume).
- Confusing the metric ton (1,000 kg) with the US short ton (907 kg).
Tips for better results
- Double-check which system a unit belongs to (for example US vs UK gallons).
- Use the swap button to convert in the opposite direction instantly.
- Bookmark the conversions you use most — each pair has its own page.
Frequently asked questions
How many milligrams are in one ounce?
One ounce equals 28,349.523125 milligrams. 28,349.523125 is the exact factor used by this converter.
How do I convert ounces to milligrams?
Multiply the value in ounces by 28,349.523125. To go the other way, multiply milligrams by 0.0000352739619496.
What is 10 oz in mg?
10 oz = 283,495.23125 mg. Also, 5 oz = 141,747.615625 mg and 100 oz = 2,834,952.3125 mg.
What is the difference between a ounce and a milligram?
An avoirdupois ounce is 1/16 of a pound, exactly 28.349523125 grams, used for food portions and postage. A milligram is one thousandth of a gram, typically used for medication doses and nutrition labels.
Is this tool free and private?
Yes — the Ounce to Milligram is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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