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Medication Dosage by Weight Calculator

Calculate weight-based dosage ranges for common over-the-counter medications. Particularly useful for children, where dosing is determined by body weight rather than age alone.

For reference only. Always confirm against the product label and consult a healthcare provider or pharmacist before administering any medication.

Calculate dose by weight

Select a medication and enter body weight to see the recommended dose range.

Important: This tool provides general reference information based on standard published dosing guidelines for OTC medications. Always read the full product label and consult a healthcare provider or pharmacist before administering any medication, especially to children. Do not use this tool as a substitute for medical advice.

Patient details

Only OTC medications with well-established weight-based dosing guidelines are included.
Enter the weight of the person being dosed.
Some medications are not recommended for children under 2, consult a doctor.
Live results update as you type
Dosage Reference

200–400 mg per dose

Acetaminophen for a 44 lb child. Every 4–6 hours as needed, max 5 doses/day.

200 mg Min dose
400 mg Max single dose
Every 4–6 hr Dosing interval

How to use this calculator

Select the medication, enter body weight in pounds or kilograms, and choose the appropriate age group. The calculator returns the recommended single dose range in milligrams, the dosing interval, and the daily maximum based on standard published OTC dosing guidelines. Always confirm against the product label before administering.

Tips for safe dosing

  • Use the proper measuring device: Always use the measuring device that comes with liquid medications. Household teaspoons vary in volume and can cause significant dosing errors.
  • Ibuprofen age restriction: Never give ibuprofen to children under 6 months old, or to anyone who is dehydrated, vomiting repeatedly, or has kidney or stomach concerns without consulting a doctor first.
  • Alternating medications: Acetaminophen and ibuprofen can be alternated for fever management in children. This is a common practice but should be discussed with a pediatrician first.
  • No aspirin for children: Do not give aspirin to children or teenagers with fever. There is a risk of Reye's syndrome.
  • Emergency preparedness: For emergency preparedness, stock both acetaminophen and ibuprofen in your medicine kit in both adult and children's formulations.
Dosing recommendations shown are based on standard published guidelines for healthy individuals. Kidney disease, liver disease, and certain drug interactions can significantly change safe dosing limits. Always read the full product label. When in doubt, call Poison Control (1-800-222-1222 in the US) or consult a pharmacist.

Weight-based dosing guidelines used

  • Acetaminophen (children): 10–15 mg/kg per dose, every 4–6 hours, max 5 doses/day (75 mg/kg/day)
  • Acetaminophen (adults): 325–1,000 mg per dose, every 4–6 hours, max 4,000 mg/day
  • Ibuprofen (children): 5–10 mg/kg per dose, every 6–8 hours, max 40 mg/kg/day
  • Ibuprofen (adults): 200–400 mg per dose, every 4–6 hours, max 1,200 mg/day (OTC)
  • Diphenhydramine (children 6–11): 12.5–25 mg per dose, every 4–6 hours
  • Diphenhydramine (adults): 25–50 mg per dose, every 4–6 hours
  • Loratadine: Fixed dose by age group, 5 mg (children 2–5), 10 mg (6+)

FAQ

Why is dosing based on weight rather than age for children?

Children of the same age can vary significantly in body weight, a 5-year-old may weigh anywhere from 35 to 55 pounds. Since drug distribution and metabolism depend on body mass, weight-based dosing is more accurate than age-based dosing. Age ranges on packaging are conservative estimates designed to be safe for the lightest child in that age bracket.

Is it safe to give children's acetaminophen to adults?

Yes, the active ingredient is identical, only the concentration differs. Adults taking children's liquid formulations would need to calculate the correct volume based on the concentration on the label. Adult tablets are generally more convenient and accurate for adults. The key constraint for adults is staying under 4,000 mg total per day (or 3,000 mg/day for regular drinkers).

Can I give ibuprofen and acetaminophen together?

They work by different mechanisms and can be taken simultaneously at full doses, or alternated on a staggered schedule to maintain more consistent pain/fever relief. This is particularly common practice in pediatric fever management. However, confirm with a doctor or pharmacist if the person has any underlying health conditions or takes other medications.

What should I do if someone takes too much acetaminophen?

Acetaminophen overdose is serious and may not cause immediate symptoms but can cause severe liver damage. If you suspect an overdose, call Poison Control immediately at 1-800-222-1222 (US) or go to the nearest emergency room. Do not wait for symptoms, early treatment is critical.

What medications should I stock in an emergency kit?

A well-rounded emergency medicine kit should include: acetaminophen (adult and pediatric formulations), ibuprofen, diphenhydramine (antihistamine/allergy), loratadine (non-drowsy allergy), hydrocortisone cream (skin reactions), antacids, oral rehydration salts, and a thermometer. Store a 2–4 week supply and check expiration dates annually.