Convert Troy Ounces to Milligrams

Formula

mg = oz t × 31103.4768

Derivation from SI units:

• 1 oz t = 480 gr = 31.1034768 g (exact)
• 1 mg = 10⁻⁶ kg = 10⁻³ g
• 1 oz t = 0.0311034768 kg ÷ 0.000001 kg per mg = 31103.4768 mg

Both units are defined exactly, so the factor is exact. Troy Ounce definition: troy ounce; Milligram definition: milligram.

Worked examples

1. A reading of 2 oz t converts to 62206.9536 mg.
   2 oz t × 31103.4768 = 62206.9536 mg
2. A value of 32.15 oz t is 999976.7791 mg.
   32.15 oz t × 31103.4768 = 999976.7791 mg

Where it's used

Troy Ounces are used for gold, silver and platinum prices, while milligrams appear in medication doses (e.g. 500 mg tablets). Both measure mass (commonly called weight), so the conversion is a fixed factor.

Troy Ounce to other weight and mass units

Frequently asked questions

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 (troy or apothecary)".
• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.