How to Calculate Pediatric Dosing

Pediatric dosing describes the calculation from an adult-appropriate milligrams per kilogram per day--mg/kg/day--to child-safe dosages. Determine child-safe dosages using the child's body weight. This calculation is not always completely accurate and requires a great deal of understanding about the medication that you are administering. If you are not completely confident in your ability to determine a child-safe dose of a specific medication, do not administer the medication. Rather, consult a trained physician or pharmacist who can better calculate what dosage is safe for your child.

Step 1

Determine the medication's mg/kg/day. You can obtain this information from the drug's manufacturer. In bulk medications meant to be distributed to multiple prescriptions, the manufacturer typically prints the dosage on the side of the packaging.

Step 2

Measure the child's body weight. Though the calculation requires the child's body weight in kilograms, you may also measure in pounds and convert.

Step 3

Convert the baby's weight from pounds to kilograms by dividing the baby's weight by 2.2. For instance, a child that weighs 22 pounds weighs 10 kg.

Step 4

Multiply the baby's weight in kilograms by the mg/kg/day amount. For instance, the dosage of a 30 mg/kg/day medication given to a 22 pound child should not exceed 400 mg/day.

Step 5

Divide the dosage by the frequency that you must administer the medication. A 22 pound child who takes a 30 mg/kg/day medication in four doses per day should take 100 mg per dose.


Administering medication to your child in doses greater than recommended by the manufacturer can cause serious illness, injury or death. Do not give medication to any child unless you are completely confident that the dose is safe and appropriate. Only administer medication to a child under the direction of a trained physician or pharmacist.

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