Calculator input
The form uses a responsive grid: three columns on large screens, two on medium screens, and one on small screens.
Example data table
| Scenario | Age | Weight | Form | Strength | Illustrative dose | Illustrative note |
|---|---|---|---|---|---|---|
| Infant | 1 year 2 months | 10.50 kg | Liquid | 24 mg/mL | 157.5 mg or 6.6 mL | 15 mg/kg example with careful label checking. |
| Child | 6 years 0 months | 20.00 kg | Liquid | 24 mg/mL | 300 mg or 12.5 mL | Weight-based example using 15 mg/kg. |
| Teen | 12 years 0 months | 42.00 kg | Tablet | 500 mg | 500 mg or 1 tablet | Rounded practical tablet example. |
| Adult | 30 years 0 months | 72.00 kg | Tablet | 500 mg | 1000 mg or 2 tablets | Adult labelled example with 6-hour spacing. |
Formula used
Weight-based formula
Single dose (mg) = body weight (kg) × selected mg/kg
Dose range (mg) = weight × 10 to weight × 15
Displayed daily cap (mg) = the smaller of weight × 60 and the absolute daily ceiling used on the page.
Form conversion formula
Liquid volume (mL) = dose (mg) ÷ concentration (mg/mL)
Tablet count = dose (mg) ÷ tablet strength (mg)
Remaining allowance = daily cap − amount already taken today
How to use this calculator
- Enter age, body weight, and the product form you plan to use.
- Type the liquid concentration or tablet strength from the label.
- Choose auto, adult fixed, or weight-based dosing mode.
- Enter any paracetamol already taken today and the number of doses already given.
- Add the last dose time to estimate the next eligible time.
- Tick risk flags for liver issues, dehydration, fasting, alcohol use, pregnancy, or other combination medicines.
- Press Calculate dose to show the result above the form.
- Review warnings first, then use the CSV or PDF buttons if you need a record.
Frequently asked questions
1. Does this calculator replace a doctor or pharmacist?
No. It is an educational aid for checking arithmetic, intervals, and product strength. Children, frail adults, pregnancy, liver disease, and persistent fever still need professional judgment.
2. Why does the result change with weight?
Many pediatric calculations are weight-based. A larger or smaller body weight changes the milligram target, daily cap, and the matching liquid volume or tablet count.
3. Why does the page ask about other medicines?
Many cold, flu, and prescription products already contain paracetamol or acetaminophen. Adding those amounts together is essential because overdose risk depends on the total daily intake from every source.
4. Can I use it for infants?
Use extra caution. Young infants need product-specific labelling and clinical review. The calculator warns for infants younger than 3 months and encourages professional confirmation for very young children.
5. Why is there both an exact value and a rounded value?
The exact value shows the raw math. The rounded value helps compare the result with practical measuring devices or tablet splitting, while still reminding you to follow the actual product label.
6. What if the patient weighs under 50 kg?
Low body weight can need lower limits, especially with liver disease, alcohol use, or poor nutrition. The page warns about this and encourages a pharmacist or clinician review.
7. Why does the calculator show a daily cap?
The daily cap helps prevent accidental overdose. It compares the new dose against the amount already taken today and estimates how much allowance may still remain.
8. When should someone get urgent help?
Get urgent advice after any suspected overdose, double dosing, unclear product duplication, worsening illness, trouble breathing, persistent vomiting, yellowing skin, confusion, or a child who seems unusually drowsy.