Amoxicillin Pediatric Dosage Calculator

The amoxicillin pediatric dosage calculator is designed to automatically calculate the appropriate dose of amoxicillin to be given to a child. The doses are calculated based on the weight of the child.

This Amoxicillin pediatric dose calculator can also be referred to as any of the following:

• amoxicillin 125mg/5ml dosage for child calculator
• amoxicillin 200mg/5ml dosage for child calculator
• amoxicillin 250mg/5ml dosage for child calculator
• amoxicillin 400mg/5ml dosage for child calculator

It is designed to calculate doses for Amoxicillin oral suspension of any brand, based on the child’s body weight.

How To Use This Calculator

1. Enter the Age of the child either in months or years and select the applicable unit.
2. Enter the Weight of the Child either in Kilograms or pounds and select the unit that applies.
3. Select the Strength of the oral suspension
4. Choose the Indication for which Amoxicillin is intended.
5. Click the Calculate Dose button to get the recommended Amoxicillin dose in both milliliters and milligrams.

What is Amoxicillin?

Amoxicillin is an antibiotic belonging to the class beta-lactam. It works by preventing susceptible bacteria from forming cell walls, hence resulting in their breakdown and death.

Amoxicillin is well tolerated. It is absorbed fast and reaches peak blood concentration in 1 to 2 hours. Amoxicillin has a very short half-life of approximately 61.3 minutes.

To prevent falling and rising of drug level in the blood, it is administered every 8 to 12 hours (three times a day), unlike most other antibiotics. Amoxicillin is approved by the FDA for use in the treatment of:

• Skin and skin structure infections, 
• Urinary tract infection, 
• Ear, nose, and throat infection
• Helicobacter pylori eradication in ulcer patients
• Acute bacterial sinusitis
• Lower respiratory tract infection.

It also has some off-label uses such as in the management of Lyme disease and periodontitis.

Amoxicillin dosage charts by weight

The dosage of amoxicillin varies depending on the condition treated. Below is a chart showing the pediatric doses of amoxicillin for various disease conditions.

Condition	Age/Weight	Dosing	Duration
Ear, Nose, & Throat Infections	<3 months	≤30 mg/kg/day PO divided q12hr for 48-72 hours; ≥10 days for S. pyogenes infections	Standard 10-day course for severe symptoms or age <2 years
	>3 months and <40 kg	25 mg/kg/day PO divided q12hr or 20 mg/kg/day PO divided q8hr	5-7-day course for mild or moderate AOM in >2 years
	>40 kg	500 mg PO q12hr or 250 mg PO q8hr	10-14 days
Severe Infections	<3 months	≤30 mg/kg/day PO divided q12hr for 48-72 hours; ≥10 days for S pyogenes infections	Standard 10-day course for severe symptoms or age <2 years
	>3 months and <40 kg	45 mg/kg/day PO divided q12hr or 40 mg/kg/day PO divided q8hr	10-14 days
	>40 kg	875 mg PO q12hr or 500 mg PO q8hr	10-14 days
Acute Otitis Media	≥2 months and children	80-90 mg/kg/day PO in divided doses q12hr	10 days for pneumonia, 5-7 days for mild or moderate AOM in >2 years
Lower Respiratory Tract Infections	<3 months	≤30 mg/kg/day PO divided q12hr for 48-72 hours; ≥10 days for S. pyogenes infections	Standard 10-day course for severe symptoms or age <2 years
	>3 months and <40 kg	45 mg/kg/day PO divided q12hr or 40 mg/kg/day PO divided q8hr	10-14 days
	>40 kg	875 mg PO q12hr or 500 mg PO q8hr	10-14 days
Pneumonia, Community-acquired	<3 months	Safety and efficacy not established
Empiric	≥3 months	90 mg/kg/day PO divided q12hr	10 days
Group A Streptococcus	≥3 months	50-75 mg/kg/day PO divided q12hr	10 days
H. influenza	≥3 months	75-100 mg/kg/day PO divided q8hr	10 days
S. pneumoniae (mild infection or step-down therapy)	≥3 months	90 mg/kg/day PO divided q12hr or 45 mg/kg/day divided q8hr	10 days
Infective Endocarditis (Prophylaxis)	–	50 mg/kg PO 30-60 min before procedure	–

How to calculate amoxicillin dosage for a child

To calculate amoxicillin dosage, you will need to know the correct dose for the child, the Indication (what the child is being treated for), and the strength of the amoxicillin oral suspension (found on the label of the product).

Example

Let’s assume we want to calculate the dose of amoxicillin to administer to a 5-month-old baby weighing 30 kg who is being treated for a throat infection. The recommended dose here is 20 mg/kg/day, divided every 8 hours.

Here is the summary of the required details to make this calculation:

• Age: 5 months old
• Weight: 30 kg
• Diagnosis: Throat infection
• Recommended dose: 20 mg/kg/day divided every 8 hours

We will use the following amoxicillin suspensions/concentrations for our calculations:

• 125 mg/5 mL
• 200 mg/5 mL
• 250 mg/5 mL
• 400 mg/5 mL

Calculating the Total Daily Dose

First, we calculate the total daily dose based on the recommended mg/kg/day dose:

• Recommended dose: 20 mg/kg/day
• Patient weight: 30 kg
• Total Daily Dose:
  • 20 mg/kg/day x 30 kg = 600 mg/day total

Calculating Each Divided Dose

Next, we calculate the amount needed for each dose based on dividing over 24 hours:

• We are dividing every 8 hours
• So 24 hours ÷ every 8 hours = 3 divided doses per day
• Total daily dose is 600 mg
• 600 mg per day ÷ 3 divided doses = 200 mg per dose

Okay, now we know this patient needs a total amoxicillin dose of 600 mg per day, with each of the 3 divided doses needing to provide 200 mg.

Let’s use this info to calculate the volume needed from different amoxicillin concentrations…

Amoxicillin 125mg/5ml Child Dose Calculation

• Desired dose: 200 mg per dose
• Concentration: 125 mg per 5 mL
• Use ratio and proportion:
  • (X ml of solution) * (125 mg/5 mL) = 200 mg
  • Cross-multiply:
    X * 125 mg = 1000 mg
    X = 1000 mg/125 mg per 5 mL X = 8 mL

Each dose should be 8 mL of 125mg/5mL amoxicillin suspension.

Amoxicillin 200mg/5ml Child Dose Calculation

• Desired dose: 200 mg per dose
• Concentration: 200 mg per 5 mL
• Set up ratio:
  • (X mL solution) * (200 mg/5 mL) = 200 mg
  • No need to cross-multiply because ratio is 1:1
  • X mL = 5 mL

Each dose should be 5 mL of 200mg/5mL amoxicillin suspension.

Amoxicillin 250mg/5ml Child Dose Calculation

• Desired dose: 200 mg per dose
• Concentration: 250 mg per 5 mL
• Set up ratio:
  • (X mL solution) * (250 mg/5 mL) = 200 mg
• Cross-multiply:
  • X * 250 mg = 1000 mg
  • X = 1000 mg/250 mg per 5 mL
  • X = 4 mL

Each dose should be 4 mL of 250mg/5mL amoxicillin suspension.

Amoxicillin 400mg/5ml Child Dose Calculation

• Desired dose: 200 mg per dose
• Concentration: 400 mg per 5 mL
• Set up ratio:
  • (X mL solution) * (400 mg/5 mL) = 200 mg
• Cross-multiply:
  • X * 400 mg = 800 mg
  • X = 800 mg/400 mg per 5 mL
  • X = 2 mL

Each dose should be 2 mL of 400mg/5mL amoxicillin suspension.

References

• Medscape: Amoxicillin Dose and Uses