Medication Dosage Calculator
Work out a weight-based dose in mg and the volume of liquid medicine to give, as a double-check.
About the Medication Dosage Calculator
Many medicines, especially for children, are dosed in mg per kg of body weight. The volume to measure out depends on the liquid's strength, written as mg per mL (or mg per 5 mL). Always use the measuring device that comes with the medicine.
The formula
Dose (mg) = mg/kg × weight (kg); volume (mL) = dose ÷ (mg per mL)
Worked example
Paracetamol 15 mg/kg, child 18 kg, liquid 160 mg/5 mL
- Dose = 270 mg
- Volume = 270 ÷ 32 = 8.44 mL
Things to keep in mind
- This is a calculation aid, not a prescription. Always follow the dose on the label or from your doctor or pharmacist, and never exceed the maximum daily dose.
Questions people ask
Why weight rather than age?
Weight tracks how a child's body handles the drug more closely; age bands on labels are approximations.
Is a kitchen teaspoon accurate?
No. Use an oral syringe or the cup supplied with the medicine.