None. Milligram is a unit of dry measure, and milliliter is a unit of liquid measure. That said, you could have a milliliter of fluid that contains (some number of) milligrams of a medication.
See the link for a metric equivalency table.
Edit:
You can do the conversion easily, if you have the density of the sustance.
3 millilitres is equal to 3,000 milligrams.
3 millilitres is equal to 3,000 milligrams.
The units are incompatible. Milligrams measure mass, millilitres measure volume.
1.2 millilitres
2 millilitres.
The prescribed limit is:35 micrograms of alcohol per 100 millilitres of breath.80 milligrams of alcohol per 100 millilitres of blood.107 milligrams of alcohol per 100 millilitres of urine.
A minim is a unit of capacity, not of mass. In the United States, it is equal to one sixtieth of a dram, or 0.0616 millilitres, rounded to three significant figures. In the United Kingdom, it is equal to one twentieth of a scruple, or 0.0592 millilitres.
'milligrams' is a measure of mass/weight. 'millilitres is a measure of liquid volume. You need to know the density of the substance in order to compare grams and litres.
Mg is weight(milligrams) while ml is volume(millilitres), so it will depend on the density of the substance.
It would be 4 millilitres.
There are 1000 milligrams in one gram. Therefore, 0.25 grams is equal to 0.25 x 1000 = 250 milligrams.
The prefix "milli" means a "thousandth" Thus there are: One thousand milligrams in a gram. One thousand milliliters in an liter. Armed with this information the answer is obvious (hint - multiply 1.6 by 1000). Therefore the answer is 1600 millilitres