Calculate weight-based drug doses for adults and children. Supports mg/kg, mcg/kg dosing.
⚠️ For educational purposes only. Always consult a qualified healthcare professional before making clinical decisions.
kg
mg/kg
mg/mL
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Single Dose
Daily Total Dose
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Volume per dose
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Patient Weight
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Frequency
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About This Drug Dosage Calculator
This free drug dosage calculator computes medication doses based on patient weight (mg/kg dosing), body surface area (mg/m² dosing) and standard fixed-dose calculations for clinical reference.
Accurate drug dosing is fundamental to patient safety. Weight-based dosing is particularly important in paediatrics, oncology, and for medications with narrow therapeutic indices.
Dosing Principles in Clinical Practice
Key principles: always verify calculated doses against maximum recommended doses; adjust for renal and hepatic impairment; consider ideal body weight vs actual body weight for obese patients (drug-dependent); double-check high-alert medications with a colleague. This calculator is a reference tool — always verify against current prescribing guidelines.
Frequently Asked Questions
Should I use actual or ideal body weight for dosing?+
This is drug-dependent. Hydrophilic drugs (aminoglycosides, vancomycin) use adjusted body weight in obesity. Lipophilic drugs may require actual body weight. Always check drug-specific guidelines.
What is the difference between mg/kg and mg/m² dosing?+
mg/kg dosing is simpler and commonly used. mg/m² (body surface area) dosing is used for chemotherapy and some paediatric drugs as it correlates better with physiological parameters across body sizes.
How should doses be adjusted in renal impairment?+
Many drugs require dose reduction or extended dosing intervals in renal impairment. The adjusted dose renal calculator and drug-specific references (e.g. Therapeutic Guidelines, MIMS) should be consulted.
Is this calculator safe for paediatric dosing?+
This calculator provides reference calculations. Paediatric dosing requires careful verification — always cross-reference with current paediatric formularies and clinical guidelines.
What are high-alert medications?+
High-alert medications (e.g. insulin, concentrated electrolytes, anticoagulants, opioids, chemotherapy) require extra precautions including independent double-checking before administration.