Q:

# What is the difference between a milligram and a milliliter?

A:

A milligram measures mass while a milliliter measures volume. Mass relates to weight, or the amount of matter in a thing, while volume is how much space a substance takes up. This comparison is similar to comparing a pound (weight) to a cup (volume).

## Keep Learning

Credit: REB Images Image Source Getty Images

A milligram is 1,000th of a gram or 1,000,000th of a kilogram. In the metric system, each type of measurement has a basic unit. Usually, it is the unit without a prefix (such as the meter for length), but in the case of mass, it is the kilogram. For volume, the basic unit is the liter, though sometimes cubic meters are used instead. Volume is measured by multiplying length times width times height, so a cubic meter is a meter cubed (a meter times a meter times a meter).

Generally, a person cannot make a conversion between these two units. To make a conversion, the density of what is being weighed must be known. Density is how tightly packed molecules are in a certain substance. For instance, water expands when it floats, which is why ice floats in water. Therefore, water that has the same mass can take up more space if it is frozen, meaning it takes up more milliliters. In fact, density is often measured in grams per cubic meter.

Sources:

## Related Questions

• A:

Because the milliliter is a unit of volume, and grams are a unit of mass, the answer to this question depends on what material one is measuring. For one of the most common materials, water, the conversion is simple. Because 1 milliliter of water equals 1 gram of mass, 300 milliliters of water weighs 300 grams.

Filed Under:
• A:

A milliliter is a measurement of volume, while a gram is a measurement of mass. Therefore, it is impossible to convert between the two measures without additional information. However, one can determine the mass if the density of the substance in question is known.

Filed Under:
• A:

The conversion of milligrams to milliliters is dependent on density and can be found using the formula volume = mass/density, where the volume is in milliliters, the mass in milligrams and the density in milligrams per milliliter. The various densities of different substances give different mass to volume ratios.