What is the correct formula for calculating a medication dosage when given concentration and desired dose?

• A. Dose = Concentration × Volume
• B. Volume required = Dose ÷ Concentration
• C. Volume required = Desired dose × Available volume
• D. Dose required = (Desired dose / Available concentration) × Available volume

Answer: (A)

The key idea is that the amount of drug you deliver (the dose) comes from how concentrated the solution is and how much volume you give. In math terms, Dose = Concentration × Volume. This relationship is the foundation for dosage calculations: it shows that dose scales with both how concentrated the medicine is and how much you administer.

If you know the desired dose and the concentration, you can still work with the same relationship by rearranging to Volume = Dose ÷ Concentration. For example, a solution at 5 mg/mL used to reach a 25 mg dose requires 25 ÷ 5 = 5 mL. The direct form Dose = Concentration × Volume is the simplest way to express how these quantities connect, and other rearrangements just solve for a different variable while coming from the same equation.