Youngs Rule uses age. (which makes it easier to remember, the word young refers to age)
Here is the formula:
Adult Dose X (Age ÷
(Age+12)) = Child's Dose
Example 11 year old girl / 70 Lbs
500mg X (11 ÷ (11+12)) = Child's
500mg X (11 ÷ 23) = Child's Dose
500mg X .48 = Child's Dose
Child's Dose =
Young's rule video tutorial By Zita Schmitt, CPhT
Dosage based on weight
Often drugs are prescribed based on an adults or childs weight in order to more accurately dose. The calculation is very simple and easy to perform. However, you must pay close attention to whether the dosage has been prescribed per Kg or Lbs.
Example: 132 Lb
woman is prescribed Acyclovir 5mg/kg
Accurate dosage calculations are very important in pharmacy. The tutorial on this website is strictly for the purpose of practicing and preparing for the PTCB or ExCPT exams. Pharmacy Technicians are relied on to calculate standard and non-standard dosages every day.
However, a pharmacist is ultimately responsible for all medications and will have the final call on which methods, formulas and calculations are to be used. This website is for informational, educational and entertainment purposes only. Always consult a licensed medical doctor or pharmacist before determining any dosage calculation. If you have any questions, please use the contact page