What this calculator does
This tool estimates a single dose of infant Tylenol (acetaminophen) based on your child's body weight. Acetaminophen is dosed by weight, not age, because two children of the same age can weigh very different amounts. The standard pediatric range is 10–15 mg per kilogram per dose, and this calculator uses 15 mg/kg as the default target while also showing the full safe range. Dosing guidance here reflects common US pediatric practice and the US infant oral suspension strength of 160 mg/5 mL.
How to use it
Enter your child's weight and choose kilograms or pounds. Leave the dose per kg at 15 mg/kg (or lower it within the 10–15 range if advised). The concentration defaults to 32 mg/mL, which equals the standard 160 mg per 5 mL infant suspension; change it only if your product label states a different strength. The calculator returns the dose in both milligrams and milliliters, plus the acceptable range.
The formula explained
First the dose in milligrams is found: mg = weight in kg × mg/kg. If you entered pounds, weight is converted with 1 lb = 0.4536 kg. Then the liquid volume is computed: mL = mg ÷ concentration. With the 32 mg/mL suspension, every 32 mg of medicine is contained in 1 mL of liquid.
$$\text{Dose (mL)} = \frac{W \times \text{Dose (mg/kg)}}{\text{Concentration (mg/mL)}}$$ $$\text{where}\quad W = \text{Weight (kg)}$$
Worked example
A baby weighs 8 kg. At 15 mg/kg the dose is \(8 \times 15 = 120\) mg. Using the 160 mg/5 mL (32 mg/mL) suspension: \(120 \div 32 = 3.75\) mL. The 10–15 mg/kg range would be 80–120 mg, or 2.5–3.75 mL.
FAQ
How often can I give it? Acetaminophen can usually be given every 4–6 hours, with no more than 5 doses in 24 hours. Follow your pediatrician's instructions.
My infant is under 3 months old — is this safe? Do not give acetaminophen to infants under 12 weeks without first speaking to a doctor, as fever in young infants needs evaluation.
What if my product is a different strength? Always check the label. Children's liquid is often the same 160 mg/5 mL, but chewables and other forms differ. Enter the correct mg/mL or ask your pharmacist.
