Ounces to Milligrams Converter

About the oz to mg calculation

One ounce is exactly 28,349.52 milligrams, so converting between them is a single multiplication. Enter any value above and the result updates as you type. Common in US recipes and for postal weights. Not the same as a fluid ounce. The usual unit for medication doses and nutrient quantities.

Formula

mg = oz × 28,349.52

1 oz = 28,349.52 mg
1 mg = 0.00003527 oz

Worked example

To convert 16 oz, multiply by 28,349.52: 16 × 28,349.52 = 453,592.37 mg.

Frequently asked questions

How many milligrams are in a ounce?

There are 28,349.52 milligrams in one ounce. To convert any amount, multiply the number of ounces by 28,349.52.

How do I convert milligrams back to ounces?

Divide instead of multiplying, or equivalently multiply by 0.00003527. One milligram is 0.00003527 ounces.

Is this conversion exact?

Yes. Since the international agreement of 1959, the relationship between ounces and milligrams is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.

Where is each of these units used?

Ounces: common in US recipes and for postal weights. Not the same as a fluid ounce. Milligrams: the usual unit for medication doses and nutrient quantities.

Sources

• NIST Special Publication 811 — Guide for the Use of the International System of Units