# Pediatric Dosage Calculator

Calculate pediatric medication doses by weight. Supports mg/kg/dose and mg/kg/day dosing with maximum dose checks and liquid volume calculations.

## What this calculates

Children's medication doses are almost always calculated by body weight because a standard adult dose would be too much for a smaller body. Enter your child's weight and the prescribed mg/kg dose to calculate the correct amount per dose and per day, with optional max dose safety checks.

## Inputs

- **Child's Weight** (kg) — min 1, max 100 — Child's body weight
- **Dose per kg** (mg/kg) — min 0.01, max 200 — Prescribed dose in mg per kg of body weight
- **Dosing Basis** — options: mg/kg/dose (per single dose), mg/kg/day (total daily dose) — Whether the prescribed dose is per single dose or per entire day
- **Doses per Day** — options: Once daily, Twice daily (BID), Three times daily (TID), Four times daily (QID), Every 4 hours
- **Maximum Single Dose (optional)** (mg) — min 0, max 5000 — Maximum allowed single dose (from drug reference). Leave blank if unknown.
- **Liquid Concentration (optional)** (mg/mL) — min 0, max 1000 — For liquid medications, enter concentration to calculate volume

## Outputs

- **Single Dose** — Amount of medication per single dose
- **Total Daily Dose** — Total medication amount per day
- **Liquid Volume per Dose** — formatted as text — Volume of liquid medication per dose
- **Max Dose Check** — formatted as text — Whether the calculated dose exceeds the maximum allowed
- **Important Notice** — formatted as text — Medical safety disclaimer

## Details

Pediatric dosing by weight (mg/kg) is the foundation of safe prescribing for children. Unlike adults, who often receive standardized doses, children span a wide weight range from 3 kg newborns to 80+ kg teenagers, making fixed doses impractical and potentially dangerous.

There are two common ways prescriptions are written. "mg/kg/dose" means each individual dose equals the child's weight multiplied by the prescribed amount -- for example, 10 mg/kg/dose given 3 times daily for a 20 kg child means 200 mg per dose, 600 mg per day. "mg/kg/day" means the total daily amount equals weight times the prescribed amount, then divided among doses -- the same 20 kg child at 30 mg/kg/day divided into 3 doses also gets 200 mg per dose.

Maximum dose caps are critical safety checks. Even though a heavy child might calculate to a very high dose by weight, most medications have absolute maximum single and daily doses. For example, ibuprofen is dosed at 10 mg/kg but should not exceed 400 mg per dose or 1200 mg per day regardless of weight. Always verify maximum doses in a current drug reference.

DISCLAIMER: This calculator is for educational reference only. Pediatric medication dosing should always be verified by a pharmacist or prescribing physician. Dosing errors in children can have serious consequences. Never administer medication to a child without proper medical guidance.

## Frequently Asked Questions

**Q: What is the difference between mg/kg/dose and mg/kg/day?**

A: mg/kg/dose means the calculated amount is for each individual dose. If a 20 kg child needs 10 mg/kg/dose three times daily, they get 200 mg per dose, totaling 600 mg/day. mg/kg/day means the calculated amount is the total for the entire day, divided among doses. The same child at 30 mg/kg/day divided into 3 doses also gets 200 mg per dose. The distinction is important because confusing the two can double or triple the intended dose.

**Q: Why do children need weight-based dosing?**

A: Children's bodies process medications differently than adults, and their organ systems are still developing. A dose that is safe for a 70 kg adult could be dangerous for a 15 kg child. Weight-based dosing scales the amount proportionally to body size, helping achieve effective drug levels without overdosing. For some medications, body surface area (BSA) is used instead of weight for even more precise dosing.

**Q: What if my child is overweight?**

A: For overweight or obese children, some medications should be dosed using ideal body weight rather than actual weight, because fat tissue does not metabolize all drugs equally. Water-soluble drugs (like amoxicillin) may need actual weight, while lipophilic drugs may distribute differently in excess fat. Your pediatrician or pharmacist can advise on which weight to use for a specific medication.

**Q: How should I measure liquid medication?**

A: Always use the measuring device that comes with the medication, such as an oral syringe or dosing cup. Household teaspoons vary in size and should never be used. One teaspoon is approximately 5 mL, but actual kitchen spoons can range from 3 to 7 mL, which is a huge margin of error for a child's dose. Oral syringes are the most accurate option for small volumes.

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Source: https://vastcalc.com/calculators/health/pediatric-dose
Category: Health & Fitness
Last updated: 2026-04-08