Pediatric Medication Dose Calculator (mg/kg)
Compute a pediatric medication dose from weight and a mg/kg rate, with a configurable adult cap and per-dose/per-day breakdown. Verify against your formulary before administration.
= 15.00 kg
Refs: Harriet Lane Handbook (23rd ed.), Lexicomp Pediatric & Neonatal Dosage Handbook, BNF for Children. Clinical decision support tool — verify against the formulary entry for the specific drug, indication, and patient; not a substitute for clinical judgment.
Home pediatric essentials
Amazon affiliateAlways verify dosing with your pediatrician.
As an Amazon Associate we may earn from qualifying purchases. This does not add cost for you.
Home pediatric essentials
Amazon affiliateAlways verify dosing with your pediatrician.
As an Amazon Associate we may earn from qualifying purchases. This does not add cost for you.
About this tool
Pediatric drugs are usually prescribed per kilogram of body weight, with a maximum adult-equivalent dose that the per-kg calculation may not exceed. This calculator walks through the four common steps in one place: enter the child's weight in kg (or lb, which the tool converts), enter the per-kg dose for the chosen medication from your formulary, set the frequency per day (the number of divided doses), and set the adult cap if the formulary specifies one. The tool reports the single-dose mg, the total daily mg, and whether the dose is capped — capping happens when the weight-based calculation would exceed the adult maximum, and most pediatric formularies want you to fall back to the adult cap in that case. The mg-to-volume conversion is included for liquid formulations: enter the concentration in mg/mL and the tool reports the per-dose volume. This is a clinical decision support tool — confirm dosing with reference texts (Harriet Lane Handbook, Lexicomp, BNFc) and your institution's formulary; not a substitute for clinical judgment.
How to use it
- Enter the child's weight (kg or lb).
- Enter the per-kg dose from the formulary (e.g. 15 mg/kg).
- Set frequency per day (the number of divided doses).
- Optionally set an adult cap (e.g. 1000 mg) and a liquid concentration (mg/mL).
Frequently asked questions
- What is the adult cap and why does it matter?
- Most pediatric drugs have a maximum single dose and maximum daily dose set by the adult ceiling — once a child is heavy enough that weight-based dosing exceeds that ceiling, the formulary tells you to give the adult dose instead. The calculator flags this and shows both numbers so you can decide.
- Should I use ideal body weight or actual weight?
- Depends on the drug. Most pediatric protocols use actual body weight (ABW), but in obese children some drugs (aminoglycosides, vancomycin) use adjusted body weight. The formulary entry for the specific drug will state which.
- How does the liquid concentration field work?
- If you enter a concentration in mg/mL, the calculator converts the per-dose mg into a per-dose volume (mL). This is the volume the nurse or caregiver actually measures.
- What about loading doses and titration?
- This calculator computes a flat mg/kg single + daily dose. Loading doses, titration ramps, and renal-adjusted doses need the specific protocol from your formulary.
- Why is it dangerous to round mg/kg doses?
- In small children a 10% rounding error can be a 10% medication error — non-trivial for narrow-therapeutic-window drugs (digoxin, theophylline, vancomycin). The calculator reports unrounded values; round per your institution's policy.
- Is any data sent anywhere?
- No. All calculation runs in your browser.