Convert Ounce to Milligram
Convert ounces to milligrams instantly. 1 ounce = 28349.5231 milligram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Milligram to Ounce converter for the reverse conversion.
Units explained
Ounce
The (avoirdupois) ounce (oz) equals one-sixteenth of a pound, about 28.35 grams.
From Latin 'uncia', meaning a twelfth part.
US food portions, postal weights, and boxing weight classes.
Standardized as 1/16 of the international pound from 1959.
Milligram
A milligram (mg) equals one-millionth of a kilogram, or 0.001 gram.
From the SI prefix 'milli-' (from Latin 'mille', thousand).
Standard for medicine dosing, nutrition labels, and fine jewelry.
Part of the original metric system of 1795.
Ounce to Milligram conversion formula
The relationship between ounces and milligrams:
To convert ounces to milligrams, multiply the value in ounces by 28349.5231. To reverse, multiply milligrams by 3.527396e-5.
How to use this converter
Type a value into the calculator. The result in milligrams updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Milligram to Ounce converter for the reverse direction.
Step-by-step: convert ounces to milligrams
- Write down the value in ounces (oz).
- Multiply that value by the factor 28349.5231.
- The product is the equivalent value in milligrams (mg).
- To reverse, multiply the milligram value by 3.527396e-5.
Worked examples
Example 1 — Convert 1 oz to mg:
1 × 28349.5231 = 28349.5231 mg
Example 2 — Convert 100 oz to mg:
100 × 28349.5231 = 2834952.3100000001 mg
Real-world example — Adjacent metric sub-units
One ounce equals 1,000 milligrams. Engineers move between these scales constantly: PCB feature sizes in the larger unit, wire-bond diameters in the smaller.
1 oz × 28349.5231 = 28349.5231 mg
Real-world example — Adjacent small-scale precision
One ounce equals 1,000 milligrams — the standard sub-millimeter precision conversion that materials engineers use whenever they switch between bulk material thickness specs (larger unit) and surface-finish characteristics (smaller unit).
1 oz × 28349.5231 = 28349.5231 mg
Ounce to Milligram conversion table
Standard reference values for converting ounces to milligrams:
| Ounce [oz] | Milligram [mg] |
|---|---|
| 0.01 | 283.495231 |
| 0.1 | 2834.95231 |
| 1 | 28349.5231 |
| 2 | 56699.0462 |
| 3 | 85048.5693 |
| 4 | 113398.0924 |
| 5 | 141747.6155 |
| 10 | 283495.231 |
| 20 | 566990.4620000001 |
| 30 | 850485.6930000001 |
| 40 | 1133980.9240000001 |
| 50 | 1417476.155 |
| 100 | 2834952.3100000001 |
| 500 | 1.417476e+7 |
| 1000 | 2.834952e+7 |
Frequently asked questions
How many milligrams is 1 ounce?
How do I convert ounces to milligrams?
How do I convert milligrams back to ounces?
How many milligrams is 100 ounces?
Popular weight unit conversions
Convert Ounce to other weight units
Show all Ounce conversions
Metric / SI (18 units)
Avoirdupois (14 units)
Troy & Apothecary (10 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 oz = 28349.5231 mg) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.