How many milligrams are in a milliliter?

Answer 1

.15

Answer 2

The number of milligrams in a milliliter depends on the substance being measured because different substances have different densities. Milligrams and milliliters measure different things - milligrams measure weight and milliliters measure volume.

Answer 3

it depends on the density

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Millilitre is a unit of volume and milligram is a unit of mass; they are not compatible.

The volume is the ratio mass/density.

So if you want to know the answer looking for first to this density.

Answer 4

No answer is possible because grams are mass and liters are volume. You must stipulate a material (or at least a density) to get an answer.
If the substance were water with a density of 1 then:
1000 mg (of water density 1) are in 1 ml
A milliliter (ml) is a unit of volume whereas a milligram (mg) is a unit of mass. In order to answer this question you would need to specify the substance as the answer will vary by the substance density.
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.

Some people still believe that there is a conversion in relation to water but that is only approximately true. Until 1964 a litre was defined as the volume of one kilogram of pure water at 4 deg Celsius and at a pressure of 760 millilitres of Mercury. With that definition 1 milligram of water (under those conditions) would have occupied 1 ml. But that definition of a litre was abandoned in favour of 1 litre =1000 cubic centimetres.