Medication Dosage Calculator
Calculate weight-based medication dosage (mg/kg). For educational reference only — always follow prescriber instructions.
Did this tool work for you?
How to use this calculator
Weight-based dosing multiplies the prescribed dose per kilogram by patient weight to get the total daily dose. This is divided by the dosing frequency to get each individual dose. Volume per dose is then calculated from the medication concentration.
- 1
Enter the patient's weight in kilograms and the dose in mg/kg as prescribed by the clinician.
- 2
Select the dosing frequency and enter the concentration of the medication formulation.
- 3
Enter the treatment duration to see the total course dose. Always verify results with the prescribing clinician.
Frequently asked questions
What is weight-based dosing and when is it used?
Weight-based dosing calculates the medication amount as a proportion of body weight (mg/kg) to ensure appropriate drug exposure across patients of different sizes. It is especially important in paediatrics, oncology, and critical care where a one-size dose would be too much for small patients or too little for large ones.
How do I find the dose per kg for a medication?
The dose per kg is specified in the prescriber's orders or the medication's official prescribing information (package insert). Never estimate or assume this value. Different conditions, patient populations, and renal or hepatic function can all change the appropriate dose per kg.
Is this calculator safe to use for actual patient dosing?
No. This calculator is for educational and training purposes only. All medication dosing decisions must be verified by a licensed prescriber, pharmacist, or qualified clinical professional using the current prescribing information and the patient's complete clinical picture. Double-check all calculations before administration.
Medication Dosage Calculator — Weight-Based Dosing Reference
Understanding Weight-Based Medication Dosing
Weight-based dosing is a fundamental pharmacological principle used to individualise drug therapy. By expressing dose as milligrams per kilogram of body weight, clinicians account for the fact that drug distribution, metabolism, and elimination all correlate with body size. This approach is standard practice in paediatrics (where children range from 1 kg neonates to 80 kg adolescents), oncology (where chemotherapy has narrow therapeutic windows), infectious disease (where antibiotic efficacy depends on achieving target concentrations), and critical care medicine. This calculator helps healthcare students and professionals quickly verify weight-based dose calculations for educational and reference purposes.
How to Calculate Volume per Dose from Concentration
Many liquid medications are supplied as a solution with a known concentration expressed in milligrams per millilitre (mg/mL). To determine how many millilitres to draw up, divide the calculated dose in milligrams by the concentration. For example, if a child needs 250 mg of a drug supplied at 125 mg/5 mL (25 mg/mL), the volume is 250 ÷ 25 = 10 mL. This calculator automates this step, but all results must be independently verified by a qualified health professional before any medication is administered.
Learn more from an authoritative source:
CDCIV Drip Rate Calculator
Calculate IV drip rate in mL/hr and drops/min for nursing and clinical reference.
eGFR Calculator (Kidney Function)
Estimate glomerular filtration rate (eGFR) using the CKD-EPI formula to assess kidney function.
Body Surface Area Calculator
Calculate body surface area (BSA) using Mosteller, DuBois, and Haycock formulas. Used for drug dosing and clinical assessment.
Blood Pressure Category Checker
Check your blood pressure reading against AHA/JNC 8 guidelines and understand what it means.
Blood Glucose to HbA1c Calculator
Convert between average blood glucose levels and HbA1c percentage for diabetes monitoring.
Pediatric BMI Calculator
Calculate BMI for children aged 2–18 with weight-for-age percentile interpretation.
Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →