Children's medicines are dosed by weight: milligrams of drug per kilogram of body weight, capped at the adult maximum and spaced by the labelled interval. This educational calculator shows how mg/kg dosing works — the actual dose for your child always comes from the product label, your pharmacist or your pediatrician, never a website.
Children’s medicines are dosed by body weight, not by age — a 4-year-old who weighs 20 kg and one who weighs 14 kg need genuinely different amounts. This pediatric dose calculator shows how weight-based (mg/kg) dosing works for educational purposes, so parents understand the numbers on the label and why the pharmacist asks the child’s weight.
One rule stands above everything on this page: the product label and your pediatrician or pharmacist always decide the dose — never a website. Use the calculator to understand the principle, then read on.
Pediatric Dose (Weight-Based)
Estimated single dose of a medication by body weight.
How weight-based dosing works
Pediatric doses are written as milligrams of drug per kilogram of body weight per dose (mg/kg). The arithmetic is: dose = child’s weight (kg) × mg/kg for that medicine — then checked against the maximum single dose, because a large child’s weight-based dose must never exceed the adult ceiling. Timing matters as much as amount: each medicine has a minimum interval between doses and a maximum number of doses per 24 hours.
Why children are not small adults
A child’s liver enzymes, kidney clearance and body water differ from an adult’s — and change continuously through childhood — so scaling an adult dose down by weight alone can still be wrong for the youngest children. This is why infant formulations differ from children’s formulations, why some drugs are simply prohibited under certain ages, and why aspirin is never given to children with viral illness (Reye’s syndrome risk). It is also why concentration matters: infant drops and children’s syrup of the same medicine can have different strengths, and mixing them up is a classic dosing accident.
The rules that prevent real accidents
- Always use the dosing device in the package — kitchen teaspoons vary from 2.5 to 7 ml.
- Dose by weight, using the label table; use age only when weight is unknown.
- Check the concentration (mg per ml) every single time — especially when switching between infant and children’s products.
- One adult in charge of medicine times, written down — double-dosing happens when two caregivers each “give the evening dose”.
- Check combination products — cold remedies may already contain paracetamol; giving both is an overdose route.
- Never call medicine candy, and store everything locked and high.
When not to dose at home at all
Some situations skip the medicine cabinet and go straight to medical care: any fever in a baby under 3 months; a child who is unusually drowsy, has a stiff neck, a non-blanching rash, difficulty breathing, or signs of dehydration; fever beyond 3 days; or any suspected dosing error or accidental ingestion (call your poison control line immediately). When in doubt, a phone call to your pediatrician beats any calculation. Acibadem’s pediatrics specialists are available for everything from routine dosing questions to urgent assessment.
This tool is educational only. It illustrates how weight-based dosing works — it is not a prescription and must not be used to determine an actual dose. The correct dose for your child comes from the product label, your pharmacist or your pediatrician. If you suspect an overdose, contact emergency services or a poison control center immediately.
Frequently asked questions
How are children’s medicine doses calculated?
By body weight: the prescribed mg/kg multiplied by the child’s weight in kilograms, capped at the medicine’s maximum single dose and given no more often than the labelled interval.
Why does the pharmacist ask my child’s weight and not just age?
Because children of the same age vary enormously in weight, and weight predicts drug handling far better. Age-based label tables are the fallback for when weight is unknown.
Can I give adult tablets in smaller amounts?
No — splitting adult formulations is inaccurate and some adult products are unsafe for children entirely. Use pediatric formulations and their measuring devices.
What if my child vomits right after a dose?
Do not automatically re-dose — whether to repeat depends on the medicine and the timing. Call your pharmacist or pediatrician for that specific case.
What should I do if I gave too much?
Contact your national poison control line or emergency services immediately, with the product packaging in hand — even if your child seems fine. Some overdoses show symptoms late.
Numbers are a starting point — not a diagnosis
If your results raise questions, Acibadem specialists can review your situation properly: share your case and receive a free, no-obligation medical opinion from the relevant department.