Paediatric Dosing Calculator
Weight-based paediatric dosing with BNFC cross-check. Supports mg/kg, mcg/kg, and per-day or per-dose regimens.
Calculate paediatric doses using weight-based dosing, Clark's rule, or Young's rule.
Formula
Dose = Weight (kg) × Dose per kg, divided by the prescribed frequency
Always check against the BNFC age band and maximum dose. Ideal body weight in obesity.
Step-by-step method
- 1
Find the BNFC entry
Look up the drug in the BNFC and identify the dose for the child’s age band and indication.
- 2
Confirm the child’s weight
Use the most recent recorded weight in kg. Centile-derived weight is used only when actual weight is unavailable.
- 3
Multiply weight by dose per kg
Dose per administration = Weight × Dose per kg.
- 4
Apply the maximum cap
Compare against the BNFC maximum daily and per-dose limits — do not exceed adult dose.
- 5
Round to a measurable volume
Round to a volume that can be measured accurately with the supplied oral syringe.
Worked example
Scenario: Amoxicillin 25 mg/kg three times daily for an 18 kg child.
Answer: 18 × 25 = 450 mg per dose; 1350 mg total daily.
Practice calculations for the CRA
500+ exam-style calculation questions with detailed explanations, mapped to the GPhC Common Registration Assessment Part 1.