What is the mg/kg Dosage Calculator?
The mg/kg dosage calculator works out a weight-based medication dose by multiplying a prescribed dose rate (in milligrams per kilogram) by the patient body weight. Weight-based dosing is widely used in pediatrics, chemotherapy, anesthesia, and many antibiotic regimens because the appropriate amount of drug scales with body size.
This tool is a general arithmetic aid for education and quick estimation. It is not medical advice. Always confirm doses against the prescriber order, the drug label, and a clinical reference before administration.
How to use it
Enter the dose rate in mg/kg, the patient body weight, and choose kilograms or pounds (pounds are converted using 1 lb = 0.45359237 kg). Optionally add the number of doses per day to see the total daily dose, and a liquid concentration in mg/mL to see the volume to draw up per dose.
The formula explained
The core equation is $$\text{Dose (mg)} = \text{Dose per kg} \times \text{Body weight (kg)}$$ If a liquid concentration \(C\) (mg/mL) is supplied, the volume per dose is \(V = \text{Dose} \div C\). The total daily dose simply multiplies the single dose by the number of administrations per day.
Worked example
A child weighs 20 kg and the order is 15 mg/kg per dose. $$\text{Dose} = 15 \times 20 = 300 \text{ mg}$$ per administration. Given three doses per day, the daily total is \(300 \times 3 = 900\) mg/day. If the syrup is 100 mg/mL, the volume is \(300 \div 100 = 3\) mL per dose.
FAQ
Does it handle pounds? Yes — select "Pounds" and the weight is converted to kilograms automatically.
What if I leave frequency or concentration blank? Those rows are simply hidden; the single dose is still calculated.
Is this safe for clinical use? It is an estimation aid only. Verify every dose against authoritative sources and watch for maximum dose limits, which this tool does not enforce.
