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.

Cowling’s Rule Formula

The following formula is used to calculate the appropriate dosage of medication for children according to Cowling’s Rule.

CD = (AD * A) / (A + 12)

Variables:

  • CD is the child’s dose (mg)
  • AD is the adult dose (mg)
  • A is the child’s age in years

To calculate the child’s dose, multiply the adult dose by the child’s age in years. Then, add 12 to the child’s age. Divide the first result by the second result. This will give you the appropriate dosage for the child according to Cowling’s Rule. However, this rule should be used with caution as it may not be accurate for all medications or for very young children.

What is Cowling’s Rule?

Cowling’s Rule is a mathematical formula used to calculate the appropriate dosage of medication for children. It is based on the child’s age and is often used when specific pediatric dosing information is not available. The rule states that the child’s dose is equal to the adult dose multiplied by the child’s age in years, divided by the child’s age plus 12. This rule is not universally accepted and should be used with caution, as it may not be accurate for all medications or for very young children.

How to Calculate Cowling’s Rule?

The following steps outline how to calculate the Cowling’s Rule.


  1. First, determine the adult dose (AD) in milligrams (mg).
  2. Next, determine the child’s age (A) in years.
  3. Next, use the formula CD = (AD * A) / (A + 12) to calculate the child’s dose (CD) in milligrams (mg).
  4. Finally, calculate the Cowling’s Rule.
  5. 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.

adult dose (AD) = 200 mg

child’s age (A) = 8 years