Pediatric Medication Dosage Calculator
Calculates the volume of liquid medication to give a child based on weight, recommended dose, and drug concentration. Use it when preparing common pediatric medicines like acetaminophen or amoxicillin at home or in a clinical setting.
About this calculator
Weight-based dosing is the standard approach in pediatrics because a child's ability to metabolize drugs scales closely with body mass. The prescriber or drug label provides a recommended dose in mg per kg of body weight. Multiplying that figure by the child's weight in kg gives the total milligrams needed: total dose (mg) = childWeight (kg) × dosagePerKg (mg/kg). Liquid pediatric formulations are labeled by concentration, commonly expressed as mg per 5 mL. Dividing the required milligrams by the concentration converts the dose to a volume: volume (mL) = total dose (mg) / concentration (mg/5mL). The full formula is: volume = round[(childWeight × dosagePerKg / concentration) × 100] / 100. Always cross-check the calculated dose against the maximum single dose listed in the drug's package insert.
How to use
Example: a 20-kg child needs ibuprofen at 10 mg/kg, and the suspension has a concentration of 100 mg/5 mL. Step 1 — Total dose: 20 kg × 10 mg/kg = 200 mg. Step 2 — Convert concentration to mg/mL: 100 mg / 5 mL = 20 mg/mL. Step 3 — Volume needed: 200 mg / 20 mg/mL = 10 mL. Round to two decimal places: 10.00 mL. Give 10 mL of the ibuprofen suspension per dose. Always use a calibrated oral syringe, not a household spoon.
Frequently asked questions
How do I calculate the correct acetaminophen dose for my child by weight?
The standard pediatric acetaminophen dose is 10–15 mg per kg of body weight, given every 4–6 hours as needed, with a maximum of 5 doses in 24 hours. For a 15-kg child at 15 mg/kg, the total dose is 225 mg. If the children's suspension is 160 mg per 5 mL (32 mg/mL), you would give 225 / 32 ≈ 7 mL. Never exceed the package's stated maximum dose for age and weight, and avoid using adult formulations in children.
Why is weight-based dosing important for children instead of a fixed dose?
Children are not simply small adults — their organ systems, especially the liver and kidneys responsible for drug metabolism and elimination, develop progressively. A fixed dose sized for an average child could be toxic for a small infant or completely ineffective for a large adolescent. Weight-based dosing anchors the prescription to the individual child's physiology, producing a therapeutic drug concentration with an acceptable safety margin. This is why pediatric drug labels always include a mg/kg guideline alongside the absolute maximum dose.
What does medication concentration in mg per 5 mL mean and why does it matter?
The concentration label tells you how many milligrams of active drug are dissolved in every 5 mL of liquid. This matters enormously because the same drug can come in multiple strengths — for example, amoxicillin suspension is available as 125 mg/5 mL, 200 mg/5 mL, and 400 mg/5 mL. Giving a dose calculated for one concentration using a bottle of a different concentration could mean delivering half or double the intended amount. Always read the concentration on the specific bottle you have in hand before measuring.