Medication Dosage Calculator (mg/kg)
Enter weight, the prescribed mg/kg and the liquid concentration to work out the volume.
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Medication Dosage Calculator (mg/kg) by TheCalcTools
How the Medication Dosage Calculator (mg/kg) works
Weight-based dose = body weight × mg/kg. If the prescription is a daily amount, divide by the number of doses. The volume of liquid = dose ÷ concentration (mg per mL).
This is an arithmetic aid only. Always follow the prescriber’s instructions and the product label, check units carefully, and never exceed a maximum dose. Use an oral syringe, not a kitchen spoon.
The formula
Worked example
Using the default values shown in the calculator:
| Body weight | 18 |
|---|---|
| Prescribed dose (mg/kg) | 15 |
| Dose is per | Single dose |
| Doses per day | 3 |
| Liquid strength (mg) | 120 |
| per volume (mL) | 5 |
| Maximum single dose (mg, optional) | 0 |
- 18 kg × 15 mg/kg = 270 mg.
- At 120 mg per 5 mL (24 mg/mL): 11.25 mL.
Result:
| Volume per dose (mL) | 11.25 |
|---|---|
| Dose per administration (mg) | 270.0 |
| Total per day (mg) | — |
| Capped at the maximum? | No |
Frequently asked questions
Can I use this to decide a child's dose?
No. Only a doctor or pharmacist should set a dose. Use this to check the arithmetic of a dose you have been given.
Sources and further reading
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This calculator gives general estimates for information and education. It is not medical advice and does not diagnose anything. Talk to a qualified health professional about your own situation. See our disclaimer.