About Medication Dosage Calculator

Calculate medication dosages based on patient weight and prescription frequency. Part of the DevTools Surf developer suite. Browse more tools in the Calculators collection.

Use Cases

• Calculate weight-based doses for pediatric antibiotic or analgesic prescriptions.
• Convert between common dosage forms (tablet strength, liquid concentration, IV dilution).
• Verify that a dose falls within the therapeutic range for a given age and weight.
• Estimate dosing intervals for renally-adjusted medications based on creatinine clearance.

Tips

• Always verify calculated doses against the manufacturer's prescribing information and local clinical guidelines — this tool supports calculation, not prescription.
• Use the weight-based dosing mode for pediatric patients — pediatric doses are almost always calculated in mg/kg rather than fixed adult doses.
• Double-check unit conversions (mcg vs. mg, mL vs. L) before entering values — unit errors are the most common cause of dosing calculation mistakes.

Fun Facts

• Weight-based pediatric dosing was standardized in the US after the 1937 Elixir Sulfanilamide disaster — 107 deaths from improperly formulated medication led directly to the Federal Food, Drug, and Cosmetic Act of 1938.
• The 'Rule of 6s' (now discouraged) was once used in pediatric ICUs to quickly calculate continuous drug infusions but was found to produce 10-fold dosing errors and was replaced by standardized concentration protocols in the 2000s.
• IV medication errors account for approximately 54% of all medication errors in hospital settings (Joint Commission, 2018). Smart pump dose-error-reduction software, first introduced in 2003, reduced IV errors by 73% in adopting hospitals.

FAQ

Is this tool for professional use?

The calculator assists trained clinicians with dosage math. It does not replace clinical judgment, drug interaction checking, or prescribing authority. Always verify against current clinical guidelines and consult a pharmacist.

Does it handle renal dose adjustment?

Yes — enter eGFR or serum creatinine to compute Cockcroft-Gault creatinine clearance, then apply renally-adjusted doses for medications with renal dosing guidance.

What's the difference between mg/kg and mg/kg/day?

mg/kg is a single dose. mg/kg/day is divided across the number of doses per day. For a 10 mg/kg/day medication given every 8 hours (q8h), each dose is 10/3 ≈ 3.3 mg/kg.