There can be no equivalence.
A milligram is a measure of mass. A millilitre is a measure of volume. The two measure different things and, according to basic principles of dimensional analysis, conversion from one to the other is not valid.
If you are not convinced, consider a millilitre of air. How many milligrams?Next consider a millilitre of water. How many milligrams?
The masses of equal volumes of the two substances will clearly be very different. So there is no direct conversion between mass and volume: you need to know the density of the substance to enable you to carry out the conversion.
Many people believe that there is an exact conversion for pure water: that is not true. It is only an approximation and that has been the case since 1964 when the definition of the litre was changed.
This cannot be sensibly answered. A milliliter (mL or ml) is a measure of volume, mg is a measure of weight or mass.
1 ml
Only if the density or concentration is 1 mg/ml
This is not a valid conversion. Milliliters (mL or ml) and liters (L) are measures of volume. Grams (g), kilograms (kg) and milligrams (mg) are measures of weight or mass.
1 g = 1000 mg so 125 g = 125*1000 mg = 125,000 mg. Simple!
You would give 4ml.
This cannot be answered directly since liter is a measurement of volume and gram is a measurement of weight or mass. However if water at 4 deg C is the reference of what is being measured, then 1 gram = 1 milliliter, therefore 125 mg = .125 ml.
75/125=0.6
125 mL = 0.5283 cups.
I am guessing you mean .125 mg of Synthroid and this is the same as 125 micorgrams. This is a common dose. 125 mg is 125,000 micrograms.
Accordingly, 1 ml = 1/7.5 mg = 0.133 mg
That is 125 ml.
84 mg/ml, or 1680 mg/20 ml
15 ml