Amoxicillin Pediatric Dose Calculator

5 min read 5 steps 7 terms 5 examples 7 FAQs single dose (mg) = weight (kg) × (indication's mg/kg/day ÷ do…

This calculator performs source-specific amoxicillin arithmetic after a clinician has selected an indication and prescription.

High YMYL Reviewed by Software checks only · Updated 2026-07-23 · 8 sources

📋

Walk-through

How to Use This Calculator

5 steps

Enter the child's weight and age

Enter the child's most recent measured weight and age in months. Pounds convert to kilograms. This reference supports ages over 3 months through 18 years; young infants need an individualized prescriber or pharmacist assessment, not a dose generated from a label ceiling.

Choose the indication

Choose the indication already selected by the clinician. Standard FDA-label regimens, acute otitis media (AOM), non-severe sinusitis and confirmed group A strep are separate references. The AOM and non-severe sinusitis presets use UCSF pediatric amoxicillin guidance, not an amoxicillin-clavulanate regimen. AOM is supported from 6 months and sinusitis from 12 months.

Set the dosing frequency

Choose the prescribed frequency and duration. For AOM, select severity: the reference is 10 days below age 2 or with severe/unknown symptoms, 7 days at ages 2-5 with non-severe symptoms, and 5 days from age 6 with non-severe symptoms. Strep and the selected sinusitis reference use 10 days. A different duration needs review; the tool does not change the prescription.

Add the suspension concentration

For liquid medicine, enter the concentration as an amount in mg per a volume in mL (for example 250 mg / 5 mL). The Suspension Volume tab has preset chips for the common FDA-approved strengths (125/200/250/400 mg per 5 mL).

Read the verdict and source badge

The displayed dose applies the reference per-dose cap. The syringe figure is a measurement example, rounded to 0.1 mL without exceeding that cap; confirm it with the pharmacist. Course totals use that rounded volume. Missing or invalid inputs, unsupported age and renal impairment withhold outputs; duration conflicts withhold course totals and exports.

⚡

Reference

Formula & Methodology

4 formulas

Single dose (indication-based, weight-scaled)

single dose (mg) = weight (kg) × (indication's mg/kg/day ÷ doses per day)

Reference dose = weight in kg multiplied by the selected daily rate, divided by doses per day. Then apply the per-dose cap. For standard-severe BID at 20 kg: 20 x (45 / 2) = 450 mg per dose. The raw arithmetic and capped result are shown separately.

Daily total and mg/kg/day

daily total = capped single dose x doses/day; actual mg/kg/day = daily total / weight

After a cap is applied, the actual daily rate can be below the original weight-based reference rate. The chart compares these two values; it does not invent a typical range or establish clinical suitability.

Volume to administer

volume (mL) = single dose (mg) ÷ concentration (mg/mL), where concentration = amount ÷ volume

Liquid amoxicillin is labeled as an amount per a volume (e.g. 250 mg / 5 mL = 50 mg/mL). Divide the dose in mg by that concentration to get the volume in mL. Example: 450 mg ÷ 50 mg/mL = 9.00 mL per dose.

Per-dose cap and safety overrides

reference dose = min(weight-based dose, source per-dose cap); unsupported clinical situations require review

Standard mild/moderate caps are 500 mg BID and 250 mg TID; standard severe caps are 875 mg BID and 500 mg TID. At 40 kg or above the standard modes display the corresponding fixed adult reference (a conservative boundary). The selected UCSF AOM and non-severe sinusitis references use 1000 mg per dose BID; CDC strep uses 1000 mg once daily or 500 mg BID. Infants age 3 months or younger and renal impairment require individual clinical review.

✓

High YMYL

Trust, Methodology & Sources

Reviewed by Software checks only · Updated 2026-07-23 · 8 sources

Editorial accountability

Author: Calculover Editorial Team - Author

Owner: Calculover Editorial Team - Editorial owner

Reviewer: Software checks only - Independent clinical review pending

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

FDA DailyMed standard mild/severe daily rates are divided by the selected supported frequency, multiplied by weight and capped at the corresponding adult reference dose; at 40 kg or above those modes use the fixed adult reference. UCSF pediatric AOM and non-severe sinusitis use amoxicillin 45 mg/kg/dose BID capped at 1000 mg/dose. CDC strep uses 50 mg/kg daily capped at 1000 mg or 25 mg/kg BID capped at 500 mg. Young infants and selected renal impairment require clinical review. Exact mL is capped dose divided by verified concentration; 0.1 mL rounding cannot exceed the cap, and course totals use rounded volume. Indication-specific duration conflicts withhold course totals and result exports. Software repair and source checking are not clinical validation.

Assumption: The selected indication correctly matches the infection being treated — the calculator has no drug database and cannot diagnose or confirm that amoxicillin is the appropriate antibiotic.

Assumption: The weight is entered in the unit selected (kg or lb) and has not been mixed up, and the age in months is accurate — young-infant screening depends on the age being correct.

Assumption: The concentration entered matches the specific product's label; the calculator does not assume any single suspension strength is universal.

Limitations & guidance

A renal-impairment selection withholds the dose. This calculator does not implement a verified pediatric renal regimen; impaired kidney function requires a prescriber or pharmacist to select the regimen. The 875 mg adult-size branch is not available in this mode.

UCSF is an institutional reference; local protocols can differ. The sinusitis choice is for clinician-selected amoxicillin in non-severe pediatric illness, not amoxicillin-clavulanate or severe sinusitis.

Pediatric dosing can also depend on renal/hepatic function, allergies (including penicillin allergy), drug interactions, and local antibiotic-resistance patterns not captured here.

Decimal-point, unit, indication, and concentration errors can cause serious harm — never use this calculator to create, change, or verify a medication dose without a licensed prescriber or pharmacist.

These software repairs have not received independent pediatric pharmacist or prescriber approval. The dates shown are editorial metadata, not clinical certification. A clinician or pharmacist must verify any proposed regimen before use.

Professional guidance: For clinical/educational reference only. Not a substitute for clinical judgment. Verify all doses with a pharmacist or current prescribing information before administering. The Amoxicillin Pediatric Dose Calculator is not medical advice, diagnosis, or treatment, and does not replace care from a licensed healthcare professional. Do NOT use this tool to self-dose a child.

Primary sources

Amoxil (amoxicillin) capsules/tablets — prescribing information - FDA / DailyMed (U.S. National Library of Medicine)

Amoxicillin for oral suspension — prescribing information - FDA / DailyMed (U.S. National Library of Medicine)

The Diagnosis and Management of Acute Otitis Media - American Academy of Pediatrics (AAP), Pediatrics 131(3):e964-e999, 2013

IDSA Clinical Practice Guideline for Acute Bacterial Rhinosinusitis in Children and Adults - Infectious Diseases Society of America (IDSA), 2012

Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis - Infectious Diseases Society of America (IDSA), 2012

Pediatric acute otitis media - UCSF Infectious Diseases Management Program

Pediatric acute bacterial sinusitis - UCSF Infectious Diseases Management Program

Clinical Guidance for Group A Streptococcal Pharyngitis - CDC

📖

Glossary

Key Terms Explained

7 terms

mg/kg/day The total daily dose per kilogram of body weight for a given indication. This is the number published in the FDA label or clinical guideline and compared against the calculated dose on the Indication Range tab.

FDA-label dosing A regimen from the amoxicillin prescribing information. FDA-label source attribution describes the source of arithmetic; it is not approval of a dose for an individual child.

Clinical-guideline dosing (not FDA label) A professional or institutional clinical reference, distinct from the FDA label. This calculator uses the named UCSF pediatric AOM and non-severe sinusitis regimens and the CDC strep regimen. Other institutions may use different caps or durations.

Per-dose cap The maximum milligrams that should be given in a single dose for an indication and frequency, regardless of what the mg/kg math produces. Protects larger children from exceeding practical or adult-equivalent ceilings.

Young-infant review Age 3 months or younger requires a prescriber or pharmacist to select the regimen. The label upper ceiling of 30 mg/kg/day is not a universal treatment dose and is not converted into administration instructions here.

Adult-weight cutoff (40 kg) In standard FDA-label modes, this calculator uses the fixed adult reference from 40 kg as a conservative boundary; the label table distinguishes above 40 kg. Guideline modes retain their own explicit caps and do not switch to an unrelated adult regimen.

Concentration How much drug is in a given volume of liquid, written as an amount per volume (e.g. 250 mg / 5 mL). Dividing the amount by the volume gives mg per mL, used to convert a dose in mg into a volume in mL.

👥

Scenarios

Real-World Examples

5 worked examples

👶

Standard mild ear infection

20 kg, 4-year-old, standard-mild indication, twice daily, 250 mg/5mL

Weight 20 kg Age 48 months Indication Standard — mild/moderate Frequency Twice daily (q12h) Concentration 250 mg / 5 mL

25 mg/kg/day ÷ 2 doses = 12.5 mg/kg per dose. Single dose = 20 × 12.5 = 250 mg. Volume = 250 ÷ 50 mg/mL = 5.00 mL. Daily total = 500 mg, which is 25 mg/kg/day — within the FDA-labeled range and well under the 500 mg per-dose cap for this frequency.

🩺

High-dose otitis media

12 kg, 18-month-old, clinician-selected AOM, twice daily, 400 mg/5mL, 10 days

Weight 12 kg Age 18 months Indication Acute otitis media - clinician-selected amoxicillin Frequency Twice daily (q12h) Concentration 400 mg / 5 mL

The UCSF pediatric reference uses 45 mg/kg per dose BID: 12 x 45 = 540 mg, below its 1000 mg cap. Exact volume is 6.75 mL at 80 mg/mL; nearest 0.1 mL is 6.8 mL (544 mg). Confirm the measuring instruction with the pharmacist. At age 18 months the reference duration is 10 days, giving a rounded-volume course estimate of 136 mL.

🦠

Strep pharyngitis, once daily

25 kg, 6-year-old, strep pharyngitis indication, once daily, 400 mg/5mL

Weight 25 kg Age 72 months Indication Strep Pharyngitis Frequency Once daily Concentration 400 mg / 5 mL

Uncapped arithmetic is 25 x 50 = 1250 mg once daily. The CDC reference cap is applied: displayed dose 1000 mg, exact and rounded volume 12.5 mL at 400 mg/5mL. The 10-day course estimate is 125 mL. The calculated reference is not a prescription.

🍼

Young-infant clinical review

5 kg, 6-week-old infant, any indication selected

Weight 5 kg Age 1.5 months

At 6 weeks, this calculator withholds administration amounts and the reference table. The label upper ceiling is not used as a universal treatment regimen. A prescriber or pharmacist must select and verify the infant dose.

🧑

Weight at the adult cutoff

42 kg, 11-year-old, standard-severe indication

Weight 42 kg Age 132 months Indication Standard — severe (ENT, skin, GU) or any lower respiratory

In the standard-severe FDA-label mode, the fixed adult reference is 875 mg every 12 hours from the conservative 40 kg boundary. The calculator does not extrapolate pediatric mg/kg arithmetic beyond that boundary. Guideline-specific modes use their own stated caps.

🔗

Reference

Cite This Calculator

APA & MLA

Use either format to cite this calculator in a paper, report, or resource list.

APA

MLA

📄

Deep Dive

How Indication-Based Amoxicillin Pediatric Dosing Works

5 chapters · 5 min read

This calculator performs source-specific amoxicillin arithmetic after a clinician has selected an indication and prescription. It applies a per-dose cap consistently to the main result, liquid conversion and weight-reference table. It does not diagnose infection, select an antibiotic or validate an individual prescription.

Why the indication matters

Standard mild/moderate and severe rates come from the FDA label. The AOM and non-severe sinusitis choices separately implement UCSF pediatric amoxicillin references: 45 mg/kg per dose twice daily, maximum 1000 mg per dose. Severe sinusitis may require amoxicillin-clavulanate, which is a different formulation and is not calculated here. The strep reference comes from CDC guidance: 50 mg/kg once daily, maximum 1000 mg, or 25 mg/kg twice daily, maximum 500 mg per dose. The indication, formulation and duration must already be selected by a licensed clinician.

Age, renal function and adult-weight boundaries

Infants age 3 months or younger and anyone with selected renal impairment require individual prescriber or pharmacist review; no administration amounts are generated. The AOM reference is supported from 6 months and the sinusitis reference from 12 months. Standard FDA-label modes use a fixed adult reference from the conservative 40 kg boundary. Guideline modes retain their own caps. Supported numeric ranges are input limits, not proof that a weight is clinically plausible.

Reading a concentration and converting mg to mL

Liquid amoxicillin is labeled as an amount of drug in a stated volume — commonly 125, 200, 250, or 400 mg per 5 mL, though no single product carries all four strengths. Divide the amount by the volume to get the concentration in mg/mL, then divide the dose in mg by that concentration to find the volume to measure. Always read the concentration printed on the specific bottle in hand — it varies by product and has been reformulated over the years.

The per-dose cap

The calculator applies the cap before computing liquid volumes and daily totals, and reports that a cap was applied. Nearest 0.1 mL rounding is reduced to the next lower graduation when it would exceed the cap. A volume that would round to zero requires a pharmacist-selected device or concentration. Course estimates use the rounded measurement, not an inconsistent exact volume. Confirm all rounding with the pharmacist. A course longer than the suspension storage period requires a fresh-supply plan.

This calculator is for educational reference only

This tool performs indication-based dosing arithmetic using published FDA-label and clinical-guideline ranges. It does not know a specific child's allergies, renal or hepatic function, drug interactions, or whether amoxicillin is the right antibiotic for their infection — that judgment belongs to a licensed prescriber and pharmacist. Use the result to check your own math and catch unit or indication mix-ups, not to decide or change a dose. For clinical/educational reference only. Not a substitute for clinical judgment. Verify all doses with a pharmacist or current prescribing information before administering.

❓

Questions

Frequently Asked Questions

7 questions

Where do the high-dose references come from?+

The separate AOM and non-severe sinusitis choices use UCSF pediatric guidance: amoxicillin 45 mg/kg per dose twice daily, capped at 1000 mg per dose. These are institutional clinical references, not amoxicillin FDA-label rates. Do not use the non-severe sinusitis choice for an amoxicillin-clavulanate prescription.

What if my child is 3 months old or younger?+

The calculator withholds administration amounts for age 3 months or younger. The FDA label upper ceiling does not determine the appropriate regimen for an individual infant. Ask the prescriber or pharmacist to select the infant dose.

What if my child weighs 40 kg or more?+

The standard FDA-label modes use the fixed adult reference from 40 kg as a conservative boundary. The AOM, non-severe sinusitis and strep modes instead retain the caps and regimens of their stated clinical sources.

How do I calculate the single dose?+

Multiply the child's weight in kilograms by the indication's mg/kg/day rate divided by the number of doses per day. For example, standard-severe dosing (45 mg/kg/day) given twice daily for a 20 kg child is 20 × (45 ÷ 2) = 450 mg per dose.

How many mL is my dose?+

Divide the dose in milligrams by the concentration in mg per mL. The concentration is the labeled amount divided by its volume — for example 250 mg / 5 mL = 50 mg/mL. So a 450 mg dose is 450 ÷ 50 = 9.00 mL. Measure with an oral syringe, not a kitchen spoon.

What if the dose exceeds the per-dose cap?+

The calculator applies the selected reference cap before showing the dose and volume, while retaining the uncapped arithmetic for explanation. Never change a prescription to match the calculator. Ask the prescriber or pharmacist to resolve any difference.

Is this a substitute for a pharmacist or prescriber?+

No. This calculator applies published FDA-label and clinical-guideline dosing formulas — it has no knowledge of a specific child's allergies, kidney or liver function, interactions, or whether amoxicillin is the appropriate antibiotic. For clinical/educational reference only. Not a substitute for clinical judgment. Verify all doses with a pharmacist or current prescribing information before administering.

Download a one-page PDF of your numbers instantly. Add your email to also get our occasional calculator tips — no spam, unsubscribe anytime. Privacy.