About infant Tylenol (acetaminophen) dosing
Infant and children's Tylenol contain acetaminophen, a fever and pain reducer that pediatric guidelines dose by body weight rather than by age or a fixed adult amount. This calculator applies the standard weight-based formula - a set number of milligrams of acetaminophen per kilogram of body weight - and converts that dose into a liquid volume for the concentration you select.
How the dose is calculated
The standard pediatric acetaminophen dose is 10 to 15 mg per kilogram of body weight per dose, repeated every 4 to 6 hours as needed, without exceeding 5 doses in 24 hours. The calculator multiplies the infant's weight in kilograms by the mg/kg figure you choose within that range to get the milligram dose: dose (mg) = weight (kg) x dose per kg (mg/kg). If you enter weight in pounds, it is first converted to kilograms (1 lb = 0.453592 kg).
Converting the dose to a liquid volume
Liquid acetaminophen is labeled by concentration, such as 160 mg per 5 mL (32 mg/mL), which has been the single concentration used for both Infants' and Children's Tylenol liquid in the US since 2011. To find the volume to give, divide the milligram dose by the concentration in mg/mL: volume (mL) = dose (mg) / concentration (mg/mL). Always measure with the dosing syringe or cup that comes with the product, and confirm the concentration printed on that specific bottle before dosing, since older or imported products may use a different strength.
Dosing frequency and daily maximum
Doses are spaced at least 4 hours apart, with a maximum of 5 doses in any 24-hour period. Because the per-dose amount is already weight-based, giving the maximum 5 doses at the upper end of the 10-15 mg/kg range approaches, but should not exceed, roughly 75 mg/kg per day - the commonly cited upper bound for total daily acetaminophen exposure in children.
When to consult a professional
This tool performs the standard weight-based arithmetic for education and planning; it does not diagnose a fever's cause or replace medical advice. Any dose for an infant under 3 months old, a dose that will be repeated for more than 2-3 days, or any uncertainty about the product's concentration should be confirmed with a pediatrician or pharmacist before giving the medication.