How is the antibiotic dose calculated?

The calculator multiplies patient weight (kg) by the standard mg/kg/day dose for the selected antibiotic and indication. The daily total is then divided by the number of doses per day to give the per-dose amount. For example, amoxicillin standard dosing is 25 mg/kg/day given in 3 doses: a 20 kg child receives 500 mg/day or 167 mg per dose.

Are these dosing guidelines up to date?

The guidelines used are based on widely referenced sources including the AAP, BNF for Children, and standard pharmacology references. However, dosing recommendations can change. Always verify with current clinical guidelines and a licensed prescriber before administering any medication.

What does the maximum dose warning mean?

Many antibiotics have an absolute maximum daily dose regardless of weight. When the weight-based calculation exceeds this cap, the tool displays the maximum dose instead and shows a warning. This prevents overdosing in heavier patients.

Can I use this for adults?

Yes. For adults, the weight-based dose is calculated the same way but is capped at the standard adult maximum dose. For very heavy adults, the tool automatically applies the maximum cap.

Is this a substitute for a doctor's prescription?

No. This tool is for educational and reference purposes only. Always consult a licensed healthcare provider before prescribing or administering any antibiotic. Dosing may differ based on renal function, age, severity of infection, and local resistance patterns.

Why is amoxicillin-clavulanate dosed differently from amoxicillin?

Amoxicillin-clavulanate (Augmentin) contains clavulanic acid which adds GI side effects. High-dose regimens (80-90 mg/kg/day) use a 7:1 formulation to limit clavulanate exposure. The dosing frequency is also typically twice daily rather than three times.

Antibiotic Dose by Weight Calculator

Name: Antibiotic Dose by Weight Calculator
Availability: InStock
Author: Nham Vu

Enter patient weight and select an antibiotic to instantly calculate the total daily dose and per-dose amount based on standard mg/kg guidelines.

Patient Details

Patient Weight

Antibiotic

For educational reference only. Always verify dosing with a licensed prescriber and current clinical guidelines before administering medication.

Enter weight and select an antibiotic to calculate the dose.

Summary

Enter patient weight and select an antibiotic to instantly calculate the total daily dose and per-dose amount based on standard mg/kg guidelines.

How it works

Enter the patient weight in kilograms or pounds — the tool converts automatically.
Select the antibiotic from the dropdown list.
Choose the indication or dosing tier if multiple options exist.
The calculator applies the standard mg/kg/day dose and divides by the dosing frequency.
Results show total daily dose (mg/day), dose per administration, and the safe dose range.
A warning appears when the calculated dose exceeds the maximum safe dose for that antibiotic.

Use cases

Calculate amoxicillin dose for a child with an ear infection.
Determine azithromycin dose for pediatric community-acquired pneumonia.
Verify trimethoprim-sulfamethoxazole dosing for a UTI by patient weight.
Check whether a prescribed antibiotic dose is within the standard mg/kg range.
Estimate antibiotic dose for an adult patient using weight-based guidelines.
Compare dosing across multiple antibiotics for the same patient weight.
Support clinical education and pharmacology learning.
Double-check a prescription before dispensing.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu