Milligrams per milliliter, or **mg/mL**, is a measurement of a solution's concentration, the amount of one substance dissolved in a specific volume of a liquid. You can find the concentration of a solution by **dividing the dissolved mass by the solution's volume.**

## What Are Solutions and Concentration?

A *solution* is composed of two parts. **A solute, or substance that is dissolved, and a solvent, the liquid in which it is dissolved.** Salt water is an example of a common solution. Solid salt,

**NaCl**, is the solute, which is dissolved in a solvent of water.

The strength of a solution is measured in concentration. Concentration shows how much mass there is of the solute per volume of the solvent. Take a salt water solution of 5.7 milligrams per milliliter. This means there are 5.7 milligrams of salt in each milliliter of water.

## Convert Your Mass to Milligrams

To find a concentration in milligrams per milliliter, **you need to find the mass of your solute in milligrams.** If your mass is already in milligrams, you can skip this step. You can quickly convert between metric mass units and milligrams. One *gram*, **g**, is equal to 1000 milligrams. One *kilogram*, **kg**, is equal to 1000 grams, or 1,000,000 milligrams. So if you have 7 grams of a substance, you can convert to milligrams by multiplying by 1,000, getting 7,000 milligrams.

You can also convert non-metric units to milligrams using different conversion formulas. Non-metric conversion formulas are a little more complicated. For instance, one ounce is equal to 28.35 grams, or 28,350 milligrams. So, to convert ounces to milligrams, you'd multiply the number of ounces by 28,350.

## Convert Your Volume to Milliliters

As you did with mass, **convert the volume of your solvent to milliliters.** One *liter*, **L**, is equal to 1,000 milliliters, and one *kiloliter* is equal to 1,000 liters, or 1,000,000 milliliters. So, .75 kiloliters of water is the same as 750,000 milliliters.

You can also convert from non-metric units to milliliters. For instance, one cubic inch is equal to 16.4 milliliters. So, if you have 12 cubic inches of a solvent, you can convert it to milliliters by multiplying it by 16.4:

**12 cubic inches x 16.4 milliliters/cubic inch = 196.8 milliliters**

So, you have 196.8 milliliters of your solvent.

## Divide Mass by Volume

You now have the mass of the solute and the volume of the solvent. To find the concentration, **divide the mass in milligrams by the volume in milliliters.**

Say you have a solution where 5 grams of sugar are dissolved in 300 milliliters of water. First, convert the mass of the sugar to milligrams. One gram is 1,000 milligrams, so 5 grams is 5,000 milligrams of sugar. Your volume is already in milliliters, so you can divide the mass of sugar by the volume of water to find the concentration:

**5,000 milligrams / 300 milliliters = 16.67 milligrams/milliliter**

So, the concentration of your solution is 16.67 milligrams per milliliter, which means there are 16.67 milligrams of sugar dissolved in each milliliter of water.