Pediatric Fever Medication Calculator
Calculate the correct acetaminophen or ibuprofen dose for a child based on weight. Helps parents and caregivers avoid under- or overdosing during fever management at home.
About this calculator
Pediatric dosing for fever reducers is weight-based rather than age-based because children of the same age can vary widely in weight, and drug toxicity is directly tied to mg per kg of body mass. For acetaminophen (Tylenol), the standard recommended dose is 15 mg per kg: Dose (mg) = weight (kg) × 15. For ibuprofen (Advil, Motrin), the standard dose is 10 mg per kg: Dose (mg) = weight (kg) × 10. Acetaminophen can be given every 4–6 hours (max 5 doses in 24 hours), while ibuprofen is given every 6–8 hours and should not be used in infants under 6 months. Both medications work by inhibiting prostaglandin synthesis, reducing fever and pain. Always verify doses against the product label concentration before measuring liquid formulations.
How to use
Suppose a child weighs 18 kg and has a fever. For acetaminophen: Dose = 18 × 15 = 270 mg. For ibuprofen: Dose = 18 × 10 = 180 mg. Children's liquid acetaminophen commonly comes as 160 mg per 5 mL, so 270 mg = 270 / 160 × 5 ≈ 8.4 mL. Children's liquid ibuprofen commonly comes as 100 mg per 5 mL, so 180 mg = 180 / 100 × 5 = 9 mL. Always use the measuring syringe included with the medication, not a kitchen spoon, to ensure accurate dosing.
Frequently asked questions
What is the maximum safe acetaminophen dose per day for children by weight?
The maximum daily acetaminophen dose for children is generally 75 mg/kg/day, not to exceed 5 doses in a 24-hour period. For a 20 kg child receiving 15 mg/kg per dose, each dose is 300 mg, and the daily maximum is 1,500 mg. Exceeding these limits significantly raises the risk of hepatotoxicity (liver damage), which is the leading cause of acute liver failure in children in the US. Parents should be especially cautious about giving combination cold and flu products that already contain acetaminophen alongside a standalone dose.
When should ibuprofen be avoided in children with fever?
Ibuprofen should not be given to infants under 6 months of age because safety data in this age group are insufficient. It should also be avoided in children who are dehydrated or vomiting frequently, as reduced kidney perfusion increases the risk of acute kidney injury with NSAIDs. Children with a history of aspirin-sensitive asthma, bleeding disorders, or kidney disease should avoid ibuprofen. During chickenpox outbreaks, ibuprofen has been associated with severe secondary bacterial skin infections and should be replaced with acetaminophen as the preferred antipyretic.
How do I convert a children's medication dose from mg to mL for liquid formulations?
First, find the concentration printed on your bottle — common concentrations are 160 mg/5 mL for children's acetaminophen and 100 mg/5 mL for children's ibuprofen. Divide the required dose in mg by the concentration in mg/mL to get milliliters: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). For example, if you need 240 mg of acetaminophen from a 160 mg/5 mL (32 mg/mL) solution: 240 ÷ 32 = 7.5 mL. Always re-read the bottle each time you buy a new product, as concentrations can vary between brands and formulations, especially for infants versus children's versions.