Pediatric Dosing Calculator
Calculate weight-based doses for common children's OTC medications. Always confirm with your child's pediatrician before administering any medication.
Consult Your Pediatrician Before Use
This calculator is for informational reference only and does NOT replace professional medical advice. Always consult your child's pediatrician or pharmacist before giving any medication. Dosing may vary based on your child's medical history, other medications, and individual health conditions. Never exceed recommended doses. In case of overdose, call Poison Control at 1-800-222-1222 or 911 immediately.
Quick Answer
Pediatric medication doses are calculated by weight, not age, because children of the same age can vary significantly in size. Standard OTC dosing: acetaminophen at 15 mg/kg every 4-6 hours, ibuprofen at 10 mg/kg every 6-8 hours, and diphenhydramine at 1.25 mg/kg every 6 hours. Always use the dosing device that comes with the medication and never use household spoons.
Enter age in months (e.g., 2 years = 24 months).
About This Tool
The Pediatric Dosing Calculator helps parents and caregivers determine appropriate doses of common over-the-counter (OTC) medications for children based on weight. Weight-based dosing is the standard of care in pediatrics because children of the same age can vary dramatically in size, making age-based dosing charts less accurate. This tool calculates doses for acetaminophen (Tylenol), ibuprofen (Advil/Motrin), and diphenhydramine (Benadryl), the three most commonly used OTC medications in pediatrics.
Why Weight-Based Dosing Matters
The American Academy of Pediatrics (AAP) recommends weight-based dosing for all pediatric medications whenever possible. A 2-year-old child might weigh anywhere from 22 to 35 pounds, and the appropriate dose varies proportionally. Underdosing is the most common medication error in pediatrics, with studies showing that up to 50% of parents give their children less than the recommended dose, resulting in inadequate symptom relief. Overdosing, while less common, carries more serious risks including liver damage (acetaminophen) or kidney injury (ibuprofen). Using the child's actual weight ensures the dose falls within the safe and effective therapeutic range.
Acetaminophen (Tylenol) Guidelines
Acetaminophen is dosed at 10-15 mg/kg per dose, given every 4 to 6 hours as needed, with a maximum of 5 doses in 24 hours. The maximum daily dose is 75 mg/kg/day or 4,000 mg/day, whichever is less. Acetaminophen is generally considered safe from birth, though dosing for infants under 3 months should always be directed by a pediatrician. It is the preferred first-line medication for fever and pain in young infants. Unlike ibuprofen, acetaminophen does not irritate the stomach and can be given on an empty stomach. However, acetaminophen overdose is a leading cause of acute liver failure, so careful attention to dosing is essential. Be aware that many combination cold and flu products contain acetaminophen, which can lead to accidental double-dosing.
Ibuprofen (Advil/Motrin) Guidelines
Ibuprofen is dosed at 5-10 mg/kg per dose, given every 6 to 8 hours as needed, with a maximum of 4 doses in 24 hours. It is not recommended for infants under 6 months of age. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that provides both pain relief and anti-inflammatory effects, making it particularly effective for conditions involving inflammation such as ear infections, teething pain, and musculoskeletal injuries. It should be given with food to minimize gastrointestinal irritation. Ibuprofen should be used with caution in children with dehydration, kidney issues, or a history of stomach problems. It should not be given to children with chickenpox due to a possible increased risk of severe skin infections.
Diphenhydramine (Benadryl) Guidelines
Diphenhydramine is dosed at 1 to 1.25 mg/kg per dose, given every 6 hours as needed, with a maximum of 4 doses in 24 hours. It is not recommended for children under 2 years of age. Diphenhydramine is a first-generation antihistamine used for allergic reactions, hives, itching, and occasional use for motion sickness. It commonly causes drowsiness, and the AAP advises against using it as a sleep aid for children. Paradoxical excitability (hyperactivity instead of drowsiness) can occur in some children. Parents should be aware that many combination allergy and cold products contain diphenhydramine, and stacking these products can lead to overdose. Newer, non-sedating antihistamines like cetirizine (Zyrtec) or loratadine (Claritin) are often preferred for daily allergy management.
When to Call the Doctor
Contact your pediatrician if fever persists for more than 3 days, if your child appears unusually lethargic or difficult to arouse, if a rash accompanies the fever, if your child is under 3 months with any fever (100.4 F or 38 C or higher), if symptoms worsen despite medication, or if you are unsure about any aspect of dosing. For allergic reactions involving difficulty breathing, swelling of the face or throat, or widespread hives, call 911 immediately as this may indicate anaphylaxis requiring epinephrine.