Enter the dosage per day, total number of days the prescription needs to last, and quantity of medication in each refill into the calculator to determine the number of refills needed.

Prescription Refill Formula

The following formula is used to calculate the number of prescription refills needed.

R = (D * T) / Q

Variables:

  • R is the number of refills needed
  • D is the dosage per day
  • T is the total number of days the prescription needs to last
  • Q is the quantity of medication in each refill

To calculate the number of refills needed, multiply the dosage per day by the total number of days the prescription needs to last. Then divide this result by the quantity of medication in each refill.

What is a Prescription Refill?

A prescription refill is a continuation of a medication that a doctor has previously prescribed, allowing the patient to continue taking the medication without having to visit the doctor again. It is typically authorized for a certain number of refills, indicated on the prescription label, and can be obtained from a pharmacy once the initial supply has been used up. The pharmacist will only refill the prescription if the doctor has approved it and it is not expired.

How to Calculate Prescription Refill?

The following steps outline how to calculate the Prescription Refill using the given formula:


  1. First, determine the dosage per day (D).
  2. Next, determine the total number of days the prescription needs to last (T).
  3. Next, determine the quantity of medication in each refill (Q).
  4. Next, gather the formula from above = R = (D * T) / Q.
  5. Finally, calculate the number of refills needed (R).
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge:

dosage per day (D) = 2

total number of days the prescription needs to last (T) = 10

quantity of medication in each refill (Q) = 30