Drug Dosage by Weight Calculator

Weight-based dosing accounts for differences in body size that affect drug distribution, metabolism, and clearance. It is especially important in pediatrics, oncology, and critical care where body size varies significantly.

Divide weight in pounds by 2.205 to get kilograms. For example, 110 lbs = 49.9 kg. Always use kilograms for dose calculations. Many medication errors occur from using pounds instead of kilograms.

mg/kg/dose is the amount per individual dose. mg/kg/day is the total daily amount. For example, amoxicillin 25 mg/kg/day divided TID means each dose is approximately 8.3 mg/kg.

Yes. Most medications have absolute maximum doses regardless of weight. For example, even if weight-based calculation yields more, ibuprofen should not exceed 800 mg per dose or 3200 mg per day in adults.