Medication Dosage Calculator

📋 How to use this calculator

1. Choose the calculation method: weight-based dosing (mg/kg), BSA-based dosing (Body Surface Area, mg/m^2), IV drip rate, or unit conversion.
2. For weight-based dosing, enter patient weight (kg), the prescribed dose (mg/kg/dose), and dosing frequency (per day).
3. For BSA, enter height (cm) and weight (kg) - the calculator computes BSA automatically using the Mosteller or Du Bois formula.
4. For IV drip rates, enter fluid volume (mL), infusion duration (minutes/hours), and the drop factor of the IV set (macrodrip 15-20 gtt/mL or microdrip 60 gtt/mL).
5. Click Calculate to see dose per administration, total daily dose, the number of tablets or mL needed, and the drip rate.
6. Tip: always verify with a pharmacist or physician. This calculator is a decision-support tool, not a substitute for clinical supervision.

🧮 Drug dosing and IV drip rate formulas

• dose_per_kg = prescribed dose (mg/kg/dose)
• weight_kg = patient body weight (kg)
• height_cm = patient height (cm)
• BSA = Body Surface Area (m^2); adult average is about 1.7 m^2
• Drop_factor = 15 or 20 (macrodrip) or 60 (microdrip) gtt/mL
• Volume_mL = total infusion fluid volume
• Time_min = infusion duration in minutes

The Mosteller BSA formula is most widely used because it is simple. Pediatric dosing usually uses mg/kg, while chemotherapy and certain specialty drugs use mg/m^2 BSA. Always verify maximum daily dose and contraindications.

💡 Worked example: 5-year-old child, 18 kg, needs acetaminophen 15 mg/kg every 6 hours and 500 mL NaCl IV over 8 hours

Result: Acetaminophen 11 mL of syrup every 6 hours (1,080 mg/day, right at the daily ceiling). NaCl infusion at 21 gtt/min or 62.5 mL/hr.

❓ Frequently asked questions

📚 Sources & references

• Pediatric Dosage Handbook - Lexicomp — Wolters Kluwer Clinical Drug Information
• FDA Drug Information for Health Professionals — U.S. Food and Drug Administration
• WHO Model Formulary for Children — World Health Organization