Pediatric Dosage Calculator

Weight-based dosing multiplies the recommended dose (in mg/kg or mg/kg/day) by the child's weight in kilograms. For example, if the dose is 10 mg/kg and the child weighs 20 kg, the daily dose is 200 mg. This is divided by the dosing frequency to get the amount per administration.

Young's Rule estimates a child's dose from the adult dose using age: Child Dose = Adult Dose × [Age / (Age + 12)]. It is primarily used for children aged 2–12 years. While convenient, weight-based dosing is generally considered more accurate and is preferred in clinical settings.

Clark's Rule estimates a child's dose based on body weight in pounds: Child Dose = Adult Dose × (Child Weight in lbs / 150). It is used mainly for radioactivity dosing and some older reference texts. Modern practice typically favors weight-based or BSA-based calculations.

Body Surface Area (BSA) dosing calculates a child's dose relative to their body surface area in m², computed from height and weight using the Mosteller formula (BSA = √(height cm × weight kg / 3600)). It is commonly used for chemotherapy and certain critical medications where weight alone may not reflect physiological variation accurately.

The standard acetaminophen dose for children is 10–15 mg/kg per dose, given every 4–6 hours as needed. No more than 5 doses should be given in a 24-hour period, and the maximum daily dose is typically 75 mg/kg/day or 4,000 mg/day, whichever is less. Always consult your pediatrician.

Ibuprofen is typically dosed at 5–10 mg/kg per dose every 6–8 hours as needed. It is not recommended for infants under 6 months of age. The maximum daily dose is 40 mg/kg/day or 2,400 mg/day. Give with food to reduce stomach upset.

Divide the required dose in mg by the concentration of the liquid in mg/mL. For example, if your child needs 150 mg and the syrup is 5 mg/mL (e.g., Tylenol 160 mg/5 mL = 32 mg/mL), divide 150 ÷ 32 = 4.69 mL. This calculator does this automatically when you enter the solution concentration.

Clinical dosing is almost always calculated in kilograms (kg). If you only know your child's weight in pounds, divide by 2.205 to convert to kg. This calculator accepts both units and converts automatically. Using the wrong unit is a common source of dosing errors, so always double-check the unit.