This pediatric dose calculator converts a dose instruction into milligrams per day, milligrams per administration, administrations per day, and liquid millilitres per administration. It supports four instruction styles: mg/kg/day, mg/kg/dose, mg/day, and mg/dose. It also converts the entered medicine concentration to mg/mL. The arithmetic is useful for checking how a written instruction relates to a liquid label, but this page cannot choose a medicine or a safe dose for a child.
Pediatric Dose Arithmetic Calculator
Convert a prescribed pediatric dose into daily, per-dose, and liquid-volume amounts.
Calculator inputs
Arithmetic only
Enter the available information
Calculated result
Result summary
Your result will appear here
Complete every required field, then select the calculate button.
Calculated volume per doseprescribed amount per dose ÷ supplied concentration
- Daily amount
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- Amount each time
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- Schedule
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- Volume each time
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Educational estimate only—not medical advice, a diagnosis, or a treatment instruction. Pediatric medication errors can be serious. This page does not prescribe; a pharmacist or qualified clinician must verify the medicine, dose, concentration, and result.
Table of Contents
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What is Pediatric Dose?
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How to Use This Calculator
- Copy the prescribed numeric dose and select the instruction type exactly as written. “Per day” and “per dose” lead to different arithmetic.
- Select the stated frequency. The page maps once, twice, three times, or four times daily and intervals from every four hours down to every hour into administrations per day.
- Enter the child’s current weight. Choose kilograms or grams; grams are divided by 1,000.
- Enter the product strength as medicine mass in a stated liquid volume. Grams are converted to milligrams, while litres, teaspoons, tablespoons, and fluid ounces are converted to millilitres.
- Select Calculate and compare the output with the prescription and pharmacy label before any medicine is given.
Use this only with an instruction supplied for that child by a qualified prescriber or an official product label that clearly covers the child’s age and weight. If any unit, frequency, concentration, maximum dose, or wording is unclear, stop and ask a pharmacist or clinician.
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Formula Used
For mg/kg/day: daily mg = dose × weight, then mg per administration = daily mg ÷ administrations per day. For mg/kg/dose: mg per administration = dose × weight, then daily mg = that amount × administrations per day. For mg/day: divide the stated daily amount by administrations per day. For mg/dose: the entered amount is already the amount per administration.
Concentration (mg/mL) = medicine mass (mg) ÷ liquid volume (mL). Liquid per administration (mL) = mg per administration ÷ concentration.
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Variables Explained
| Input | What to check |
|---|---|
| Dose | The prescribed number in milligrams under the selected dose type. |
| Dose type | Whether the number applies per kilogram and whether it applies per day or per administration. |
| Frequency | How often the medicine is to be given; intervals are converted to administrations per 24 hours. |
| Weight | Current body weight, converted to kilograms. |
| Mass and volume | The label strength, such as 250 mg in 5 mL. |
| Volume per dose | The calculated liquid amount for one administration, not a recommendation. |
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Worked Example
Assume a verified instruction says 30 mg/kg/day in three divided administrations for a 10 kg child, and the supplied liquid says 250 mg per 5 mL. Daily medicine is 30 × 10 = 300 mg/day. Dividing by three gives 100 mg per administration. The concentration is 250 ÷ 5 = 50 mg/mL. The liquid amount is 100 ÷ 50 = 2 mL per administration. All details must still be checked against the actual prescription, label, medicine-specific maximum, and supplied measuring device.
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Why Use This Calculator?
A matching calculation can help reveal a transcription or unit mistake, but it does not prove the medicine or dose is suitable. Pediatric dosing can depend on indication, age, organ function, formulation, maximum limits, interactions, allergies, and specialist guidance. Some medicines use ideal or adjusted weight, age bands, body surface area, or schedules that this simple form does not represent.
Use the oral syringe or other measuring device supplied for the product. FDA safety material warns that different liquid concentrations and mismatched devices can cause errors. If too much may have been given, a dose was repeated, or a child has severe sleepiness, breathing difficulty, seizure, collapse, or another alarming reaction, contact emergency services or the local poison service immediately.
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Common Mistakes
- Confusing mg/kg/day with mg/kg/dose.
- Using an old weight or entering grams as kilograms.
- Copying 250 mg/5 mL as though it means 250 mg in 1 mL.
- Using a kitchen spoon instead of the product’s marked measuring device.
- Using the concentration from a previous bottle; the same medicine may be sold in different strengths.
- Ignoring a medicine-specific maximum dose or special dosing interval.
- Giving a result when the prescription and package label disagree instead of checking with a professional.
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Frequently Asked Questions
Can this page tell me what dose my child should receive?
No. It only converts a dose instruction that has already been verified for that child. A prescriber or pharmacist must determine whether the medicine and dose are appropriate.
What is the difference between mg/kg/day and mg/kg/dose?
The first is the whole daily amount per kilogram and is divided among scheduled administrations. The second applies at each administration, so frequency multiplies the daily total.
Which concentration should I enter?
Use the strength printed on the exact bottle or package being used, such as 250 mg in 5 mL. Never assume a refill or another brand has the same strength.
Can I measure the result with a kitchen teaspoon?
No. Household spoons vary. Use the marked oral syringe, cup, or device supplied or recommended for that product, with units that match the instruction.
Why does the child’s current weight matter?
Weight-based arithmetic changes directly with kilograms. Children grow, and a guessed, old, or wrongly converted weight can materially change the result.
What if the calculated volume differs from the label?
Do not choose one or average them. Recheck every unit and contact the dispensing pharmacist or prescriber before giving the medicine.
What if an extra dose may have been given?
Contact the local poison service, pharmacist, clinician, or emergency service promptly and have the product package available. Do not wait for symptoms or induce vomiting unless instructed.
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