Pediatric Dosage Calculator – Safe Medication Doses for Children
Calculate safe medication dosages for children based on body weight
How to Use
- Enter the child's weight in kilograms
- Enter the prescribed medication dose per kilogram (mg/kg)
- Click calculate to see the recommended dosage
- Always verify with a healthcare professional before administration
Why Pediatric Dosing is Different
Children are not simply small adults. Their bodies process medications differently due to physiological differences in metabolism, distribution, and elimination. Pediatric dosing must account for these unique factors to ensure both efficacy and safety.
Key differences include higher body water content, immature liver and kidney function (especially in infants), different protein binding, and ongoing growth and development. These factors significantly affect how medications are absorbed, distributed, metabolized, and excreted.
Pediatric Dosing Methods
Several methods exist for calculating pediatric doses:
- Weight-based dosing (mg/kg): Most common and accurate method
- Body surface area (BSA): Used for chemotherapy and some critical medications
- Age-based dosing: Less accurate, used for over-the-counter medications
- Clark's rule, Young's rule: Historical methods, rarely used today
- Dose per dose: Some medications prescribed as fixed doses regardless of weight
Weight-based dosing (mg/kg/dose) is the gold standard for most pediatric medications because it accounts for the child's size and provides the most accurate dosing.
How to Calculate Pediatric Doses
Basic formula: Dose (mg) = Weight (kg) × Prescribed dose (mg/kg)
Example: A 15 kg child needs ibuprofen at 10 mg/kg per dose:
- Calculation: 15 kg × 10 mg/kg = 150 mg
- Recommended dose: 150 mg per dose
- Maximum frequency: Every 6-8 hours as needed
- Daily maximum: Usually 40 mg/kg/day (up to 600 mg per dose)
Always check that the calculated dose does not exceed the maximum adult dose or the maximum recommended pediatric dose for that medication.
Critical Safety Considerations
When dosing medications for children, consider:
- Verify the child's current weight - use recent measurements, not estimates
- Check maximum dose limits - never exceed adult maximum or drug-specific pediatric maximum
- Consider age-specific restrictions - some medications not approved for certain age groups
- Review dosing frequency - pediatric dosing intervals may differ from adults
- Account for renal/hepatic impairment - may require dose adjustment
- Check for drug interactions with other medications
- Use appropriate measuring devices - never use kitchen spoons for liquid medications
- Round doses appropriately based on available formulations
Common Pediatric Medications and Typical Dosing
| Medication | Typical Dose | Maximum Dose | Frequency |
|---|---|---|---|
| Acetaminophen (Paracetamol) | 10-15 mg/kg | 75 mg/kg/day or 4g/day | Every 4-6 hours |
| Ibuprofen | 5-10 mg/kg | 40 mg/kg/day or 2400 mg/day | Every 6-8 hours |
| Amoxicillin | 20-40 mg/kg/day | 90 mg/kg/day | Divided 2-3 times daily |
| Azithromycin | 10 mg/kg day 1, then 5 mg/kg | 500 mg | Once daily |
Note: These are general ranges. Always consult current prescribing information and clinical guidelines for specific dosing based on indication, age, and patient factors.
Proper Measurement Tools
Using the correct measuring device is critical for medication safety:
- Oral syringes: Most accurate for liquid medications, graduated in mL
- Calibrated droppers: Provided with some medications, use only with that specific product
- Dosing cups: Less accurate than syringes but acceptable for larger volumes
- Never use household spoons: Vary greatly in volume and lead to dosing errors
- Weight-based suppositories: Follow package directions carefully
For injectable medications, only healthcare professionals should prepare and administer doses using proper sterile technique and precise measurement.
When to Contact a Healthcare Provider
Contact a healthcare provider immediately if:
- You're unsure about the correct dose or how to measure it
- The child's weight has changed significantly since the prescription
- You suspect an overdose or gave the wrong dose
- The child has an adverse reaction to the medication
- Symptoms worsen or don't improve as expected
- You need to give multiple medications and are unsure about interactions
- The child has difficulty swallowing or keeping medication down
- The prescription seems incorrect or unclear
Frequently Asked Questions
- Why can't I just give my child half an adult dose?
- Children's bodies process medications differently than adults. Simply cutting adult doses in half doesn't account for differences in metabolism, organ function, or body composition. Weight-based dosing provides a more accurate and safer approach tailored to the child's size and developmental stage.
- How accurate do I need to be with my child's weight?
- Use the most recent accurate weight measured on a calibrated scale. Weight estimates can lead to significant dosing errors. For most medications, weights should be accurate to within 0.1-0.5 kg. When in doubt, have the child weighed at the doctor's office or pharmacy.
- What if the calculated dose seems very different from what's on the label?
- Over-the-counter medication labels often provide age-based dosing ranges, which are less precise than weight-based calculations. If there's a significant discrepancy, contact your pharmacist or healthcare provider before administering. Never exceed label maximum doses without provider guidance.
- Can I round the dose to make it easier to measure?
- Small rounding is generally acceptable (e.g., 147 mg to 150 mg) and may be necessary based on available formulations. However, always round conservatively (down for most medications, especially those with narrow safety margins). Discuss rounding with your pharmacist if unsure.
- Are the dosing calculations different for premature babies?
- Yes, premature and very low birth weight infants require specialized dosing considerations due to immature organ systems. Their medications should always be dosed under direct medical supervision in a hospital or specialized care setting. This calculator is not appropriate for premature infants.
- How do I convert my child's weight from pounds to kilograms?
- Divide the weight in pounds by 2.2 to get kilograms. For example, a 33-pound child weighs 15 kg (33 ÷ 2.2 = 15). Most medical dosing is done in kilograms, so it's helpful to know your child's weight in both units.