Enter the adult dose and the child’s age into the calculator to determine the child’s dose. This calculator can also evaluate any of the variables given the others are known.

Fried’s Rule Formula

The following formula is used to calculate the dosage of a drug for a child using Fried’s Rule.

Dc = (Da * a) / (a + 12)


  • Dc is the child’s dose (mg)
  • Da is the adult dose (mg)
  • a is the child’s age (years)

To calculate the child’s dose, multiply the adult dose by the child’s age. Then, add 12 to the child’s age. Divide the first result by the second result. This will give you the child’s dose according to Fried’s Rule.

What is Fried’s Rule?

Fried’s Rule is a method used in pediatric medicine to calculate the dosage of a drug for a child. It is based on the child’s age and is typically used for children between the ages of 2 and 12. The rule states that the child’s dose is equal to the adult dose multiplied by the child’s age, divided by the child’s age plus 12. This rule is used to ensure that children receive a safe and effective dose of medication.