Pediatric

Pediatric Dosage Calculator (mg/kg)

The paediatric drug dosage calculator computes the dose per administration and total daily dose for children based on the prescribed mg/kg dose and the child's body weight. Weight-based dosing is used for virtually all medications in paediatric practice because children's pharmacokinetics differ substantially from adults — particularly in neonates and infants. Always verify paediatric doses against a current reference such as the BNF for Children (BNFc) or Harriet Lane Handbook before administration.

Dose per Administration

Formula

Single dose (mg) = Weight (kg) × Dose (mg/kg)
Daily dose (mg) = Single dose × Frequency
📖 Formula source: Harriet Lane Handbook, 22nd ed. Elsevier; 2021. BNF for Children (BNFc); 2024.

Common Paediatric Doses (reference only)

DrugTypical DoseRoute
Paracetamol / Acetaminophen15 mg/kg Q4-6H (max 75 mg/kg/day)PO/PR
Ibuprofen5–10 mg/kg Q6-8H (max 40 mg/kg/day)PO
Amoxicillin25–45 mg/kg/day in 2–3 divided dosesPO
Ceftriaxone50–100 mg/kg/day (max 4g/day)IV/IM
Salbutamol (Albuterol)0.1–0.15 mg/kg Q4-6H (max 2.5mg)Nebulised

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Frequently Asked Questions

How do I calculate a paediatric drug dose in mg/kg?

Multiply the child's weight in kg by the prescribed dose in mg/kg to get the single dose. For example, paracetamol 15 mg/kg for a 20 kg child = 15 × 20 = 300 mg per dose. Multiply by daily frequency to get the total daily dose.

What is the maximum safe dose of paracetamol in children?

The standard dose of paracetamol for children is 15 mg/kg every 4–6 hours, with a maximum daily dose of 75 mg/kg/day (up to 4g/day in children over 50 kg). Always check the current BNFc or prescribing information for age and weight-specific limits.

⚠️ Always verify paediatric doses against a current reference (e.g. BNFc, Harriet Lane). Paediatric dosing errors are disproportionately common and dangerous — always double-check with a second nurse or pharmacist.