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Child Medication Dose Calculator — mg/kg
Giving medicine to a child is a responsibility that demands precise dose calculation based on the child's weight. Most paediatric medications — including the most widely used paracetamol and ibuprofen — are dosed in milligrams per kilogram of body weight (mg/kg). This means the same drug is given in different amounts depending on how much the child weighs, not how old they are. Our child medication dose calculator lets you work out the single dose and the total daily dose in just a few seconds. Simply enter the child's weight in kilograms, the recommended mg/kg dose (from the package leaflet or your doctor's instructions), the number of doses per day, and optionally the maximum daily dose. The calculator instantly shows how many milligrams of active ingredient can be given in one dose and in total across the whole day. If you set a maximum daily dose, the tool will flag whether the calculated total exceeds that limit — essential for paracetamol (limit: 60 mg/kg/day or 4000 mg/day) and ibuprofen (limit: 40 mg/kg/day). Note that the calculator gives results in milligrams of active ingredient, not in millilitres of syrup — always check the concentration on the packaging before measuring the medicine. Important: results are indicative. Always consult a doctor or pharmacist before giving any medication to a child, especially infants under 3 months of age.
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How we calculate the medication dose
The calculator uses the standard paediatric formula: single dose (mg) = weight (kg) × dose mg/kg, rounded to 1 decimal place. Daily dose (mg) = single dose × number of doses per day, also rounded to 1 decimal place. If a maximum daily dose is provided (> 0), the calculator checks whether the daily total exceeds that limit. The "exceeded" flag = 1 means the daily dose at the given schedule will exceed the maximum — you should then reduce the single dose or extend the intervals between doses. The result is given exclusively in mg of active ingredient. To convert to ml of syrup, divide the dose in mg by the syrup concentration (mg/ml). Example: dose 150 mg, syrup 100 mg/5 ml (= 20 mg/ml) → 150 / 20 = 7.5 ml. The calculator does not replace the package leaflet or a consultation with a doctor or pharmacist. Maximum doses vary depending on the preparation and indication — always verify with the accompanying documentation.
Example: paracetamol for a 15 kg child
The child weighs 15 kg. The doctor prescribed paracetamol at 15 mg/kg every 6 hours (4 times daily), with a maximum of 60 mg/kg/day. Calculations: • Single dose = 15 kg × 15 mg/kg = 225 mg • Daily dose = 225 mg × 4 doses = 900 mg • Maximum daily = 15 kg × 60 mg/kg = 900 mg • Exceeded = NO (900 mg = 900 mg, the limit is not breached) With Calpol syrup at 120 mg/5 ml → 225 mg = 9.4 ml (roughly a full 10 ml oral syringe). Always measure with the oral syringe included in the packaging.
Frequently asked questions about dosing medication in children
How do I calculate the paracetamol dose for my child?
Multiply your child's weight in kilograms by the recommended dose in mg/kg. The standard dose for paracetamol is 10–15 mg/kg per administration, given no more often than every 4–6 hours. The maximum daily dose is 60 mg/kg or absolutely no more than 1000 mg per single dose and 4000 mg per day. Always read the product leaflet and consult your doctor or pharmacist.
What is the ibuprofen dose for a child by weight?
Ibuprofen is used at 5–10 mg/kg per single dose, no more often than every 6–8 hours. The maximum daily dose is 40 mg/kg or 2400 mg. Ibuprofen is not recommended for infants under 3 months of age or children weighing less than 5 kg. Give the medicine with food to reduce the risk of stomach irritation.
From what weight can ibuprofen be used in children?
Ibuprofen syrup for children is usually recommended from 6 months of age or 7 kg body weight, depending on the manufacturer. Ibuprofen suppositories may have different indications. Ibuprofen is contraindicated for infants under 3 months. Before giving any medication to an infant, always consult a paediatrician.
Can paracetamol and ibuprofen be combined in children?
In some cases doctors recommend alternating paracetamol and ibuprofen for high fever — paracetamol every 4–6 h, ibuprofen every 6–8 h, without overlapping dosing windows. However, you should not combine them without a doctor's instruction. Such an approach requires a precise schedule to avoid exceeding doses.
What should I do if the daily dose is exceeded?
If the calculator shows that the calculated daily dose exceeds the maximum, reduce the single dose or extend the intervals between doses so the total daily dose stays within the limit. If accidental overdose occurs, call emergency services (999 or 112) or your national poisons centre immediately. Paracetamol overdose is particularly dangerous and can damage the liver.
When should I take my child to a doctor instead of giving medicine myself?
Seek medical advice immediately if: an infant under 3 months has a fever above 38°C; fever persists for more than 3 days despite treatment; the child is very lethargic or difficult to wake; a rash, vomiting or severe abdominal pain appears; or the child is not drinking fluids. The calculator is a support tool, not a substitute for medical advice.
Why are children's medicines dosed by weight rather than age?
Weight is a much better indicator of the appropriate dose than age, because children of the same age can differ by several kilograms, which significantly affects the blood concentration of the drug. Weight-based dosing (mg/kg) ensures a more precise and safer adjustment of therapy to the individual needs of the child.
How do I use medicines in different forms — syrup, suppositories, tablets?
Different forms of the same drug may have different concentrations (mg/ml, mg/suppository, mg/tablet), so always check the concentration on the label before measuring a dose. Measure children's syrups with the oral syringe or measuring cup included in the packaging — a kitchen teaspoon is imprecise. Doses in mg remain the same regardless of the form of the medicine.
Do pain-relief medicines affect childhood vaccinations?
Routine administration of paracetamol or ibuprofen before vaccination is not recommended, as it may reduce the immune response to some vaccines. After vaccination, if the child experiences pain or fever, medicine can be given on the doctor's advice. Do not use antipyretics prophylactically before a vaccination appointment without medical instruction.
How long can I give a child medicine without seeing a doctor?
Over-the-counter paracetamol and ibuprofen can be given to a child for a maximum of 3 days for fever and 5 days for pain, provided symptoms are improving. If fever or pain persists after this time, a doctor's visit is necessary. Never extend a course of medicine without medical consultation, especially for infants and young children.
Indicative dose only — always consult a doctor or pharmacist before giving any medication to a child. The calculator does not replace medical advice and does not account for individual indications, contraindications or the child's health status.