Practice and Tools
Pediatric Dose by Weight Calculator
Convert a weight-based pediatric dose (mg/kg) into the total mg for a given patient.
Enter values and press Calculate to see the result.
Optionally cap the result at an adult maximum and divide the total across the day's administration schedule. The tool flags neonatal weights (<3 kg) and adult-sized pediatric weights (>50 kg) so the clinician verifies the appropriate reference before administering.
Method: Total dose (mg) = mg/kg x weight (kg)
Inputs and units: Patient weight (kg or lb); dose (mg/kg); adult max (mg, optional); doses per day (optional)
Assumptions and limitations: This is a general math helper. It does not carry a drug formulary and will not warn on drug-specific maximums beyond the optional adult cap you enter.
Primary reference: Lexicomp Pediatric & Neonatal Dosing Handbook; The Harriet Lane Handbook (Johns Hopkins Hospital).
Last reviewed: October 2026
This tool performs a weight based calculation only. It does not determine whether a medication or dose is appropriate for a child. Verify the drug, indication, age, weight, formulation and concentration, dosing interval, maximum dose, and organ function considerations against an authoritative pediatric dosing reference before using the result in patient care.
Formula
Total dose (mg) = mg/kg x weight (kg)
If total > adult max (mg), total = adult max.
Per-dose (mg) = total / doses per day.
Clinical Notes
- Always verify the mg/kg range, interval, indication, and route against Lexicomp Pediatric & Neonatal, the Harriet Lane Handbook, or an institution-approved reference before administering.
- Neonatal dosing differs substantially from infant/child dosing for many drugs (e.g., gentamicin, ampicillin, acyclovir). This tool warns for weight <3 kg but does not substitute for a neonatal-specific reference.
- Many pediatric protocols transition to adult dosing at or above 40-50 kg — confirm which reference applies.
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