Dosage Calculator
This calculator computes a weight-based dose for 27 commonly prescribed pediatric medications, using the target dose (mg/kg), concentration, and maximum dose limits published for each drug. It's built for clinicians and informed caregivers who already have a target dose in mind — always confirm the result against the current package insert or your pharmacy's reference before administering.
Safety notes
- This tool supports clinical judgment — it doesn't replace it. Double-check every calculated dose against the maximum dose shown and the medication's current prescribing information before dispensing or administering.
- Weight, not age, drives the calculation. Use the most recent accurate weight available; a weight that's even a few weeks old can meaningfully change the result for a fast-growing infant.
- When in doubt, call. If a calculated dose looks unusually high or low, or a caregiver has questions about administering it, contact the prescribing physician or pharmacist before proceeding.
How weight-based dosing works
Children aren't simply small adults — their body composition, organ maturity, and metabolism change quickly as they grow, so a dose sized for one child can be too much or too little for another child of a similar age. That's why most pediatric medications are dosed from body weight, expressed as a certain number of milligrams of drug per kilogram of body weight (mg/kg), rather than from age alone. Two children of the same age can weigh very different amounts, so a weight-based calculation is generally more precise than an age-based estimate.
How to use this calculator
Select a medication, then enter your child's current weight and, where applicable, the concentration of the product on hand. The calculator applies the published target dose for that medication to the weight entered and returns a calculated amount, alongside the maximum dose for that drug. Double-check that the weight, units, and concentration you've entered match what's printed on the product label — a small entry error can meaningfully change the result.
Important limitations
This tool is a cross-check, not a prescription. It can't account for a child's medical history, other medications, allergies, or the clinical judgment of the prescriber. Always confirm any calculated dose against the prescriber's instructions and the product's current labeling before giving a medication, and never exceed the labeled maximum dose. If a result looks unexpectedly high or low, or you have any doubt at all, contact your pharmacist or your child's healthcare provider before proceeding.
Sources & references
- FDA / DailyMed — official drug labeling
- The Harriet Lane Handbook (Johns Hopkins Hospital) — pediatric dosing reference
- AAP Red Book — Report of the Committee on Infectious Diseases
These references informed the guidance on this page. They are provided for transparency and further reading; they are not endorsements, and this page is not a substitute for the advice of your child's own clinician.