Pediatric Dosing Calculator
Disclaimer: Always verify with a pharmacist or pediatrician. This tool is for reference only.
Pediatric Dosing Quick Reference — Acetaminophen
Dose at 15 mg/kg using 160 mg/5 mL liquid concentration
| Weight (lbs) | Weight (kg) | Dose (mg) | Dose (mL) | Frequency |
|---|---|---|---|---|
| 12 lbs | 5.4 kg | 80 mg | 2.5 mL | Every 4–6 hr |
| 18 lbs | 8.2 kg | 120 mg | 3.75 mL | Every 4–6 hr |
| 24 lbs | 10.9 kg | 160 mg | 5 mL | Every 4–6 hr |
| 30 lbs | 13.6 kg | 200 mg | 6.25 mL | Every 4–6 hr |
| 36 lbs | 16.3 kg | 240 mg | 7.5 mL | Every 4–6 hr |
| 44 lbs | 20 kg | 300 mg | 9.4 mL | Every 4–6 hr |
| 55 lbs | 25 kg | 375 mg | 11.7 mL | Every 4–6 hr |
| 66 lbs | 30 kg | 450 mg | 14 mL | Every 4–6 hr |
| 77 lbs | 35 kg | 500 mg | 15.6 mL | Every 4–6 hr |
| 88+ lbs | 40+ kg | 500 mg (max) | 15.6 mL | Every 4–6 hr |
How We Calculate This
This pediatric dosing calculator uses established formulas and industry-standard data to provide accurate estimates.
- Enter your specific values into the calculator fields above
- Our algorithm applies the relevant formulas using your inputs
- Results are calculated instantly in your browser — nothing is sent to a server
- Review the detailed breakdown to understand how each factor affects your result
These calculations are estimates based on standard formulas. For critical decisions, always consult a qualified professional.
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Pediatric medication dosing is based on the child's weight to ensure safety and effectiveness. Weight-based dosing accounts for the fact that children metabolize drugs differently than adults.
The basic rule:
- Acetaminophen: 10–15 mg/kg per dose, every 4–6 hours (max 5 doses/day)
- Ibuprofen: 5–10 mg/kg per dose, every 6–8 hours (max 4 doses/day, age 6 months+)
- Diphenhydramine: 1–1.25 mg/kg per dose, every 6–8 hours
- Always use the concentration printed on the package — formulations vary between brands
Never exceed the maximum daily dose regardless of the child's weight. If the calculated dose seems unusually high or low, double-check the child's weight and consult a healthcare provider. Do not give ibuprofen to infants under 6 months.
When Would You Use This Calculator?
This pediatric dosing calculator is designed for anyone who needs quick, reliable estimates without complex spreadsheets or professional consultations.
- When you need a quick estimate before committing to a purchase or project
- When comparing different options or scenarios side by side
- When planning a budget and need to understand potential costs
- When you want to verify a quote or estimate you've received from a professional
- When teaching or learning about the concepts behind these calculations
Frequently Asked Questions
How do I dose children's Tylenol by weight?
Acetaminophen (Tylenol) is dosed at 10-15 mg per kg of body weight, given every 4-6 hours as needed, with a maximum of 5 doses in 24 hours. For a 20 kg (44 lb) child, each dose would be 200-300 mg. Always check the concentration on the label.
How do I dose children's ibuprofen by weight?
Ibuprofen (Advil/Motrin) is dosed at 5-10 mg per kg of body weight, given every 6-8 hours as needed. Maximum 4 doses per day. Do not give to infants under 6 months old. For a 20 kg child, each dose would be 100-200 mg.
Should I dose by age or weight?
Always dose by weight when possible — it's more accurate than age-based dosing because children of the same age can vary significantly in weight. Age-based dosing on product labels is a rough guide when you don't know the child's exact weight.
Can I alternate Tylenol and Motrin?
Many pediatricians recommend alternating acetaminophen and ibuprofen every 3-4 hours for persistent fever. For example, give Tylenol, then 3 hours later give Motrin, then 3 hours later give Tylenol again. Always confirm this approach with your pediatrician first.
What is the difference between infant and children's formulations?
Infant drops are typically more concentrated (e.g., 160 mg/5 mL for acetaminophen) so smaller volumes can be given. Children's liquid may be less concentrated. Always check the mg/mL concentration on the package and use the correct measuring device.
What if my child vomits after taking medication?
If the child vomits within 15-20 minutes of the dose, you can generally re-dose. If it has been more than 20-30 minutes, most of the medication has likely been absorbed and you should not re-dose. When in doubt, contact your pediatrician.