Paediatric Dosage Calculator

Clark's Rule is a medical formula used to estimate a child's dose of medication based on their weight compared to an average adult weight of 70 kg (or 150 lbs). The formula is: Dose = (child weight in kg / 70) x adult dose. For example, a 20 kg child would receive (20/70) x 500 mg = 143 mg.

Young's Rule uses a child's age to estimate medication dosage: Dose = [Age / (Age + 12)] x Adult Dose. It is generally considered less accurate than weight-based methods because children's weights vary significantly at the same age. It may be used when an accurate weight is not available.

Amoxicillin is typically dosed at 25 to 45 mg/kg/day divided into doses every 8 to 12 hours for standard infections. High-dose amoxicillin for resistant otitis media may go up to 80-90 mg/kg/day. Always confirm with current prescribing guidelines.

Body Surface Area (BSA) dosing uses mg/m2 instead of mg/kg. BSA correlates better with metabolic rate and is the standard for chemotherapy drugs. The Mosteller formula calculates BSA: BSA (m2) = sqrt[(height in cm x weight in kg) / 3600]. A typical child of 15 kg and 100 cm has BSA of about 0.65 m2.

Pediatric ibuprofen is dosed at 5-10 mg/kg per dose given every 6 to 8 hours, with a maximum daily dose of 40 mg/kg. For example, a 20 kg child may receive 100-200 mg per dose. Do not exceed the adult maximum of 1200 mg/day for OTC use.

No. Many medications (like antibiotics, anticonvulsants, or chemotherapy agents) have very specific mg/kg or mg/m2 dosing that cannot be estimated by general rules like Clark's or Young's. Always use drug-specific pediatric dosing references for medications with narrow therapeutic windows.

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