Enter mass or volume and choose a density to convert between milligrams and fluid ounces (US or Imperial).

Mg to Fl Oz Conversion Calculator

Enter exactly 1 value to calculate the other

Conversion between mass and volume uses density (g/mL). Choose a substance or set Custom to enter your own.

Mg to Fl Oz Formula

Converting milligrams (mass) to fluid ounces (volume) requires density; use the following general relationship with ρ in g/mL and c as mL per fluid ounce.

\mathrm{fl\ oz} = \frac{\mathrm{mg}}{1000\,\rho\,c}
  • c (US) = 29.5735296 mL/fl oz; c (Imperial) = 28.4130625 mL/fl oz.
  • ρ is the liquid density in g/mL (e.g., water ≈ 0.9982 g/mL at 20°C).
  • mg to g: g = mg ÷ 1000; volume (mL) = g ÷ ρ.
  • Then convert mL to fluid ounces: fl oz = mL ÷ c (choose US or Imperial).

Mg to Fl Oz Conversion Notes

Milligrams of Water to US Fluid Ounces (ρ = 0.9982 g/mL)
Mass (mg) Volume (US fl oz)
1,0000.034
2,0000.068
5,0000.169
10,0000.339
25,0000.847
50,0001.694
75,0002.541
100,0003.388
125,0004.234
150,0005.081
200,0006.775
250,0008.469
300,00010.163
400,00013.550
500,00016.938
750,00025.407
1,000,00033.876
* Assumes water at 20°C (ρ = 0.9982 g/mL); 1 US fl oz = 29.5735 mL.

How do you convert mg to fluid ounces? Choose US or Imperial fl oz, then compute fl oz = mg ÷ (1000 × ρ × c), where ρ is density in g/mL and c is 29.5735296 (US) or 28.4130625 (Imperial).

How do you convert fluid ounces to mg? Rearrange: mg = fl oz × c × ρ × 1000, using c = 29.5735296 (US) or 28.4130625 (Imperial).

Example Problem

Convert 250,000 mg of olive oil to US fluid ounces.

Use the US formula: fl oz = mg ÷ (1000 × ρ × 29.5735), with ρ (olive oil) ≈ 0.918 g/mL.

fl oz = 250,000 ÷ (1000 × 0.918 × 29.5735) ≈ 9.209 fl oz