Pediatric Fever Management Calculator
Checks whether a child's temperature calls for fever medicine, whether enough time has passed since the last dose, and what the next weight-based dose of acetaminophen or ibuprofen is. Flags babies under 3 months with fever for immediate medical care.
Last updated: September 2026
Formula below · 3 sources (medlineplus.gov, healthychildren.org, aap.org) · Updated Sep 2026
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About this calculator
This calculator combines the standard safety checks for treating a child's fever at home. First, any fever (38 °C / 100.4 °F or higher) in a baby under 3 months needs urgent medical assessment, so the calculator says so instead of giving a dose. Below 38 °C there is no fever to treat. Next it checks the dosing interval: acetaminophen needs at least 4 hours between doses (no more than 5 doses in 24 hours) and ibuprofen at least 6 hours (no more than 4 doses in 24 hours); if the last dose was too recent it tells you how many more hours to wait. Otherwise it gives the weight-based dose: acetaminophen 15 mg/kg per dose up to 1,000 mg, and ibuprofen 10 mg/kg per dose up to 400 mg (only from 6 months of age). If ibuprofen was the last medicine it suggests the next ibuprofen dose; otherwise acetaminophen, with ibuprofen offered as an alternative when no medicine has been given and the child is at least 6 months old. Treat the child's comfort, not the number on the thermometer, and seek care for any red-flag signs.
How to use
A 2-year-old weighing 12 kg has a temperature of 38.5 °C. The last medicine was acetaminophen 5 hours ago. Step 1 – age over 3 months and temperature 38 °C or higher, so home treatment is possible. Step 2 – 5 hours have passed, more than the 4-hour acetaminophen interval. Step 3 – dose = 12 × 15 = 180 mg. Result: 'Acetaminophen 180 mg (15 mg/kg, max 1,000 mg)'; with 160 mg/5 mL children's liquid that is 180 ÷ 32 ≈ 5.6 mL. If only 3 hours had passed, the result would say to wait 1 more hour.
Frequently asked questions
At what temperature should you give a child fever-reducing medication?
Most pediatric guidelines suggest considering fever-reducing medication when temperature exceeds 38.5°C (101.3°F) and the child appears uncomfortable. Temperature alone is not the only factor — a child with 39°C who is playing and drinking normally may need only monitoring, while a child with 38.5°C who is listless or in pain may benefit from treatment. Infants under 3 months with any fever above 38°C should be seen by a doctor immediately regardless of other symptoms.
How long should you wait between doses of children's acetaminophen and ibuprofen?
Acetaminophen (paracetamol) should be given no more frequently than every 4–6 hours, with a maximum of 5 doses in 24 hours. Ibuprofen should be spaced at least 6–8 hours apart, with a maximum of 3–4 doses per day. Exceeding these intervals risks liver damage (acetaminophen) or gastrointestinal and kidney problems (ibuprofen). Always use the weight-appropriate dose and a proper measuring device, never a kitchen spoon.
When should a parent seek emergency care for a child with a fever?
Seek emergency care immediately if a child under 3 months has any fever, if a child of any age has a fever above 40°C (104°F) that does not respond to medication, or if the child shows a non-blanching rash, stiff neck, severe headache, difficulty breathing, persistent vomiting, seizure, or is unusually difficult to wake. A febrile seizure, while frightening, is not in itself an emergency in most cases, but the child should still be evaluated promptly. When in doubt, call your local emergency services or paediatric advice line.