Amoxicillin Pediatric Dosing Calculator
Calculate amoxicillin dosage for children by weight and indication. Shows dose per administration and suspension volume for all available formulations (125, 200, 250, 400 mg/5mL).
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Disclaimer: For educational purposes only. Not a substitute for clinical judgment. Always verify doses with current guidelines and pharmacy references.
About This Tool
What Is Amoxicillin?
Amoxicillin is a broad-spectrum aminopenicillin antibiotic and one of the most commonly prescribed medications in pediatrics. It is a first-line agent for acute otitis media, strep pharyngitis (strep throat), bacterial sinusitis, urinary tract infections, community-acquired pneumonia, and endocarditis prophylaxis in children. Amoxicillin is available as oral suspensions in multiple concentrations (125, 200, 250, and 400 mg/5mL), chewable tablets, and capsules.
How to Calculate Amoxicillin Dose for Kids
Pediatric amoxicillin dosing is weight-based, expressed as mg/kg/day. The total daily dose is calculated by multiplying the child's weight (in kg) by the recommended mg/kg/day for the specific indication. This daily total is then divided by the dosing frequency (BID = twice daily, TID = three times daily) to determine the dose per administration. Finally, the mg per dose is converted to mL based on the suspension concentration. For example, using 400mg/5mL suspension: mL per dose = (mg per dose ÷ 400) × 5.
Amoxicillin Dosage by Weight for Common Infections
For ear infections (acute otitis media), the AAP recommends high-dose amoxicillin at 80–90 mg/kg/day divided BID due to increasing antibiotic resistance. Strep pharyngitis is treated with 50 mg/kg/day (max 1000 mg/day). Sinusitis and community-acquired pneumonia also use high-dose amoxicillin (80–90 mg/kg/day BID). UTIs are treated at a lower dose range of 25–50 mg/kg/day divided TID. Dental/endocarditis prophylaxis is a single dose of 50 mg/kg (max 2 g) given one hour before the procedure.
🔑 Clinical Pearls
- High-dose amoxicillin (80–90 mg/kg/day) overcomes intermediate penicillin resistance in Streptococcus pneumoniae by achieving higher middle ear fluid concentrations.
- The 400mg/5mL concentration is preferred for children over 2 years as it reduces the volume needed, improving adherence. Younger infants may do better with 125mg/5mL or 250mg/5mL for more precise dosing.
- Always round volumes to practical increments (nearest 0.5 mL or whole mL) for ease of measurement with oral syringes.
- Maximum daily dose for most pediatric indications is 3 g/day regardless of weight. For dental prophylaxis, the single-dose max is 2 g.
- Duration of therapy varies: AOM 10 days (children <2 years) or 5–7 days (≥2 years, uncomplicated), strep pharyngitis 10 days, sinusitis 10–14 days.
Key References
- Lieberthal AS, et al. The diagnosis and management of acute otitis media. Pediatrics. 2013;131(3):e964–e999.
- Shulman ST, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis. Clin Infect Dis. 2012;55(10):e86–e102.
- Wald ER, et al. Clinical practice guideline for the diagnosis and management of acute bacterial sinusitis in children. Pediatrics. 2013;132(1):e262–e280.
- Bradley JS, et al. The management of community-acquired pneumonia in infants and children older than 3 months of age. Clin Infect Dis. 2011;53(7):e25–e76.
Formula last verified: February 2026