Convert Ounces to Milligrams
1 ounce (oz) equals 28349.52313 milligrams (mg).
1 oz = 28349.52313 mg
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk ounce to milligram converter to paste a column from Excel.
How to Convert Ounce to Milligram
- 1 oz = 28349.52313 mg
- 1 mg = 0.00003527396195 oz
- Example: convert 15 oz to mg: 15 oz = 15 × 28349.52313 mg = 425242.8469 mg
Reference conditions. oz: Avoirdupois system: 1 lb = 16 oz = 7000 grains = 0.45359237 kg exactly (1959 agreement).
Formula
mg = oz × 28349.523125
Derivation from SI units:
- 1 oz = 1/16 lb = 28.349523125 g (exact)
- 1 mg = 10⁻⁶ kg = 10⁻³ g
- 1 oz = 0.028349523125 kg ÷ 0.000001 kg per mg = 28349.523125 mg
Both units are defined exactly, so the factor is exact. Ounce definition: ounce; Milligram definition: milligram.
Worked examples
- A reading of 4 oz converts to 113398.0925 mg.
4 oz × 28349.52313 = 113398.0925 mg - A value of 12 oz is 340194.2775 mg.
12 oz × 28349.52313 = 340194.2775 mg
Ounce to Milligram conversion table
| Ounces (oz) | Milligrams (mg) |
|---|---|
| 0.25 oz | 7087.380781 mg |
| 0.5 oz | 14174.76156 mg |
| 1 oz | 28349.52313 mg |
| 2 oz | 56699.04625 mg |
| 3 oz | 85048.56938 mg |
| 4 oz | 113398.0925 mg |
| 5 oz | 141747.6156 mg |
| 6 oz | 170097.1388 mg |
| 8 oz | 226796.185 mg |
| 10 oz | 283495.2313 mg |
| 12 oz | 340194.2775 mg |
| 16 oz | 453592.37 mg |
| 20 oz | 566990.4625 mg |
| 24 oz | 680388.555 mg |
| 32 oz | 907184.74 mg |
| 64 oz | 1814369.48 mg |
Where it's used
Ounces are used for food and parcel weights in the US, while milligrams appear in medication doses (e.g. 500 mg tablets). Both measure mass (commonly called weight), so the conversion is a fixed factor.
Ounce to other weight and mass units
| Conversion | 1 oz equals |
|---|---|
| ounce to kilogram | 0.02834952313 kg |
| ounce to gram | 28.34952313 g |
| ounce to milligram | 28349.52313 mg |
| ounce to microgram | 28349523.13 µg |
| ounce to metric ton | 0.00002834952313 t |
| ounce to pound | 0.0625 lb |
| ounce to stone | 0.004464285714 st |
| ounce to short ton | 0.00003125 ton (US) |
| ounce to long ton | 0.00002790178571 ton (UK) |
| ounce to grain | 437.5 gr |
| ounce to troy ounce | 0.9114583333 oz t |
| ounce to carat | 141.7476156 ct |
Frequently asked questions
How many milligrams are in 1 ounce?
1 oz = 28349.52313 mg.
How do I convert ounces to milligrams?
Multiply the value in oz by 28349.52313. For example, 15 oz × 28349.52313 = 425242.8469 mg.
Is the oz to mg conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "ounce (avoirdupois) (oz)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Ounces to Milligrams. Retrieved October 17, 2026, from https://scientificconverters.com/mass/ounces-to-milligrams/
IEEE
Scientific Converters, "Convert Ounces to Milligrams," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/mass/ounces-to-milligrams/