Short Answer 
To convert milligrams (mg) to milliliters (mL), one must know the density of the substance, as it influences the relationship between mass and volume. The formula to convert is mL = mg / density, with density expressed in mg/mL. For example, with a density of 1 mg/mL, 500 mg is equal to 500 mL.
Step 1: Understand the Units
A milligram (mg) is a unit of mass that represents a small quantity commonly used to denote the amount of an active ingredient in medications. On the other hand, a milliliter (mL) is a unit of volume that measures the space a liquid occupies. To convert between these two units, one must recognize the need for the *density* of the substance being measured, as it dictates how mass relates to volume.
Step 2: Know the Conversion Factor
The conversion from milligrams to milliliters relies on the *density* of the specific medication, which is given in milligrams per milliliter (mg/mL). To successfully convert milligrams to milliliters, use the following steps:
- Identify the *density* of the substance in mg/mL.
- Use the formula: mL = mg / density.
Step 3: Perform the Conversion
Once you have the density, you can perform the conversion. For example, if a medication has a density of 1 mg/mL:
- A conversion of 500 mg would be: 500 mg √∑ 1 mg/mL = 500 mL.
- This means that 500 mg of this particular medication is equivalent to 500 mL.