Pediatric Weight-Based Dose Calculator

Paracetamol 10 to 15 mg/kg and ibuprofen 5 to 10 mg/kg per dose are the ranges in the WHO Pocket Book, and StatPearls gives the same figures. The calculator uses the midpoint (12.5 and 7.5 mg/kg) and shows the full range under the result. It also caps a single dose at 1,000 mg of paracetamol or 400 mg of ibuprofen, the maximum single doses in StatPearls, and caps the daily total at 4,000 mg and 1,200 mg.

UK and US sources differ. US labels such as Infants' Motrin give no dose under 6 months and say to ask a doctor. The NHS allows ibuprofen from 3 months if the baby weighs over 5 kg, but not for more than 24 hours at that age without speaking to a doctor or pharmacist. The calculator flags any age under 6 months. For paracetamol, UK labels say not to give it under 2 months, and at 2 to 3 months they allow only 2 doses, for babies over 4 kg born after 37 weeks.

US children's medicine labels say to dose by weight where possible and by age otherwise. Age tables assume a typical weight for that age, so a child who is small or large for their age can get too little or too much from them. A recent weight from a scale gives the closest result.

Pick Custom and enter the mg/kg per dose and the doses per day from the prescription. Antibiotic doses depend on the infection and how severe it is, not only on weight, so the prescriber's instructions are the reference. The calculator holds no antibiotic doses of its own.

UK labels and the American Academy of Pediatrics both say to use the syringe or measuring device that comes with the medicine. Liquids come in different strengths, such as 120 mg/5 mL and 250 mg/5 mL paracetamol, so the mg dose needs converting with the strength on the bottle. The tablet-to-liquid calculator does that step. If the amount falls between two markings, a pharmacist can say which one to use.