Free Pediatric Dose Calculator

What the Pediatric Dose Calculator Does

The Pediatric Dose Calculator is a free online tool that determines the precise volume of liquid medication (or number of tablets) a child should receive based on body weight and the prescribed dose. It acts as both a children's dosage calculator and a pediatric dose volume calculator, accepting inputs in milligrams (mg) or micrograms (μg) and returning results in millilitres (mL). Because children’s drug dosages are almost always weight‑dependent, this mg per kg dosage calculator eliminates manual arithmetic and reduces the chance of errors.

The calculator also works in reverse: if you know the volume you intend to give, you can compute the corresponding drug mass. When the medication is in tablet form, entering “1” as the volume lets the tool estimate the number of tablets per dose.

How to Use the Children’s Dosage Calculator

Follow these steps to obtain accurate pediatric medication dose results:

1. Choose the dose unit – milligrams (mg) or micrograms (μg). Remember: $1\,\text{mg} = 1000\,\mu\text{g}$.
2. Select the dosage type from the four options described below. This choice heavily influences the calculation.
3. Enter the numeric dose amount (e.g., “10” if the prescription says $10\,\text{mg/kg}$).
4. Pick the administration frequency using standard Latin‑derived abbreviations (see the frequency table).
5. Input the child’s weight in kilograms or pounds (the tool auto‑converts pounds to kg).
6. Provide the drug concentration – for instance, $120\,\text{mg}/5\,\text{mL}$. The calculator automatically converts it to mg/mL.
7. Read the results: volume per dose, volume per day, and, when applicable, the number of tablets.

Dosage Types for Child Drug Dosage by Weight

The tool supports four prescription formats commonly used in paediatrics:

• Per kilogram per day (mg/kg/day) – The total daily amount is calculated from the child’s weight and then divided equally among the day’s administrations.
• Per kilogram per dose (mg/kg/dose) – Each individual dose is computed from the child’s weight; no further division is required.
• Per day (mg/day) – A fixed daily amount that does not depend on weight; it must be split across the prescribed frequency.
• Per dose (mg/dose) – A fixed amount per administration, independent of weight and frequency.

Only the first two types use the child’s weight; the latter two rely on a predetermined mass of medication.

Dose Frequency Abbreviations

The abbreviations originate from Latin and are standard on prescriptions. The table below lists the most common ones together with their corresponding number of daily administrations.

Abbreviation	Full Latin Phrase	Meaning	Doses per Day
qD	quaque die	once daily	1
BID	bis in die	twice daily	2
TID	ter in die	three times daily	3
QID	quater in die	four times daily	4
q4 hr	quaque 4 hora	every 4 hours	6
q3 hr	quaque 3 hora	every 3 hours	8
q2 hr	quaque 2 hora	every 2 hours	12
q1 hr	quaque 1 hora	every hour	24

Calculation Formulas

All volume calculations follow the principle $\text{Volume} = \dfrac{\text{Drug mass required}}{\text{Concentration}}$. The way the required mass is derived depends on the dosage type.

For mg/kg/day:

$$V_{\text{dose}} = \frac{D_{\text{day}} \times W}{C \times N}$$

where $D_{\text{day}} = \text{mg/kg/day}$, $W = \text{weight (kg)}$, $C = \text{concentration (mg/mL)}$, and $N = \text{number of doses per day}$.

For mg/kg/dose:

$$V_{\text{dose}} = \frac{D_{\text{dose}} \times W}{C}$$

For mg/day:

$$V_{\text{dose}} = \frac{D_{\text{total/day}}}{C \times N}$$

For mg/dose:

$$V_{\text{dose}} = \frac{D_{\text{per dose}}}{C}$$

To convert a volume back to mass: $\text{Mass (mg)} = C \times V_{\text{dose}}$.

Worked Example: Paracetamol Dosing

A 20 kg child has a fever and is prescribed paracetamol at $10\,\text{mg/kg}$ per dose, given twice daily. The bottle states $120\,\text{mg}/5\,\text{mL}$.

1. Concentration: $120\,\text{mg} \div 5\,\text{mL} = 24\,\text{mg/mL}$.
2. Mass per dose: $10\,\text{mg/kg} \times 20\,\text{kg} = 200\,\text{mg}$.
3. Volume per dose: $200\,\text{mg} \div 24\,\text{mg/mL} \approx 8.33\,\text{mL}$.

If the prescription had been $10\,\text{mg/kg/day}$ (i.e., a daily total of $10 \times 20 = 200\,\text{mg}$), divided into two doses, each dose would be $200 / (24 \times 2) \approx 4.17\,\text{mL}$. This contrast shows why selecting the correct dosage type is critical.

Common Pediatric Drug Concentrations

Liquid medications for children are typically supplied in mg/mL concentrations. Familiar examples include:

• Paracetamol (acetaminophen): 120 mg/5 mL (24 mg/mL) or 250 mg/5 mL (50 mg/mL)
• Ibuprofen: 100 mg/5 mL (20 mg/mL) or 50 mg/1.25 mL (40 mg/mL)
• Amoxicillin: 125 mg/5 mL (25 mg/mL) or 250 mg/5 mL (50 mg/mL)

Always verify the exact concentration printed on the bottle before using the calculator.

Medical Disclaimer

This pediatric dose calculator is provided for informational and educational purposes only. It does not replace the advice of a qualified healthcare professional. Medication errors can have serious consequences; therefore, always consult a doctor or pharmacist before administering any drug to a child. Never rely solely on this tool for treatment decisions.