How to use this motrin dosage by weight calculator
Motrin is a common brand name for ibuprofen. For many children, ibuprofen is dosed by weight rather than age because weight-based dosing is usually more accurate. This calculator estimates a dose range and shows a typical target dose of 10 mg per kg of body weight per dose.
- Standard pediatric range: 5 to 10 mg/kg per dose every 6 to 8 hours as needed.
- Common target for fever or pain: 10 mg/kg per dose.
- Common daily limit: 40 mg/kg/day, not more than 4 doses in 24 hours.
- Always check your label concentration. Different products may have different strengths.
Important: Some children should not take ibuprofen without medical advice, including infants under 6 months, children with dehydration, kidney disease, active stomach bleeding, known NSAID allergy, or certain chronic conditions.
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Weight-based Motrin dosing chart · Safety rules and red flags · How to measure doses accurately · Frequently asked questions
Weight-based Motrin dosing chart (children’s liquid 100 mg/5 mL)
This chart uses a typical target of 10 mg/kg per dose and rounds to practical amounts. Use this as a reference only and prioritize the instructions on your child’s medication label and your pediatrician’s guidance.
| Weight |
Approx. Dose (mg) |
Children’s Liquid 100 mg/5 mL |
Chewable 100 mg |
| 12–17 lb (5.4–7.7 kg) | 50–75 mg | 2.5–3.75 mL | Not usually used |
| 18–23 lb (8.2–10.4 kg) | 80–100 mg | 4–5 mL | 1 tablet (100 mg) optional |
| 24–35 lb (10.9–15.9 kg) | 110–160 mg | 5.5–8 mL | 1 to 1.5 tablets |
| 36–47 lb (16.3–21.3 kg) | 160–210 mg | 8–10.5 mL | 1.5 to 2 tablets |
| 48–59 lb (21.8–26.8 kg) | 220–270 mg | 11–13.5 mL | 2 to 2.5 tablets |
| 60–71 lb (27.2–32.2 kg) | 270–320 mg | 13.5–16 mL | 2.5 to 3 tablets |
| 72–95 lb (32.7–43.1 kg) | 330–400 mg | 16.5–20 mL | 3 to 4 tablets |
| 96+ lb (43.5+ kg) | 400 mg typical max single OTC dose | 20 mL | 2 adult tablets (200 mg each) |
Dose interval: every 6–8 hours as needed. Do not exceed 4 doses in 24 hours unless your clinician says otherwise.
Motrin dosing safety: what every parent and caregiver should know
1) Weight-based dosing is usually safer than age-only dosing
Children vary widely in body size at the same age, so age-only instructions can be less precise. A motrin dosage by weight calculator helps convert body weight into milligrams, then into mL or tablets for your exact product concentration.
2) Always verify concentration before giving a dose
Ibuprofen comes in multiple formulations. A dose in mg stays the same, but the volume in mL changes with concentration. If concentration is misread, overdose risk increases quickly. Read the front and back label every time, especially when switching brands or bottle sizes.
3) Use the right measuring device
Use an oral syringe or dosing cup that came with the medicine. Household teaspoons are unreliable and can cause underdosing or overdosing. Accurate measurement matters, especially in infants and smaller children.
4) Keep track of timing
Ibuprofen is usually given every 6 to 8 hours as needed. If fever persists, families sometimes accidentally redose too early. Write down each dose time and amount, particularly overnight or when more than one caregiver is involved.
5) Know when to avoid ibuprofen
- Infants younger than 6 months unless a clinician specifically recommends it.
- Children with significant dehydration (vomiting, diarrhea, poor intake).
- Known kidney disease, stomach ulcers, bleeding risks, or NSAID allergy.
- History of severe asthma triggered by NSAIDs.
6) Understand fever care goals
Fever itself is often part of the body’s immune response. The goal is comfort and hydration, not always making temperature perfectly normal. If your child is playful, drinking fluids, and breathing comfortably, this is reassuring. Seek medical advice if symptoms are severe, persistent, or concerning.
How the calculator estimates dose
This page uses a conservative standard pediatric framework often used in clinical settings:
- Lower-end dose: 5 mg/kg per dose
- Typical target dose: 10 mg/kg per dose
- Dose interval: every 6–8 hours as needed
- Daily ceiling: up to 40 mg/kg/day and no more than 4 doses/day
- Single-dose cap shown here: 400 mg for OTC self-care contexts unless clinician-directed
Because product labels, local guidelines, and individual health conditions vary, this calculator should be treated as a planning tool. Final dosing decisions should follow your pediatrician or pharmacist.
Practical tips to avoid dosing mistakes
- Store only one active ibuprofen product in easy reach to prevent duplicate dosing.
- Check all combination cold/flu medicines for hidden NSAIDs.
- Use one consistent unit system during calculation (kg or lb), then convert once.
- Create a simple dosing log with time, amount, and child response.
- If vomiting occurs right after dosing, ask your clinician before repeating.
- If fever lasts more than 3 days or pain worsens, arrange medical evaluation.
Frequently asked questions about Motrin dosage by weight
Can I use this Motrin dosage by weight calculator for adults?
Yes, it can estimate mg by weight, but adult OTC labeling usually uses fixed doses. Most OTC adult single doses are commonly capped at 400 mg, and total daily OTC limits are commonly lower than prescription limits unless directed by a clinician.
How often can I give ibuprofen?
Typically every 6 to 8 hours as needed, with no more than 4 doses in 24 hours unless your clinician says otherwise.
Is Motrin the same as ibuprofen?
Motrin is a brand name. The active ingredient is ibuprofen, an NSAID used for fever, pain, and inflammation.
Should I dose by age or weight?
Weight-based dosing is generally more accurate in children. If your child’s measured dose differs from age table estimates, verify with your pediatrician or pharmacist.
Can I alternate acetaminophen and ibuprofen?
Some clinicians recommend alternating in selected situations, but schedules can become confusing and increase error risk. Do this only with clear professional instructions.
Medical disclaimer
This page provides educational information only and is not medical advice, diagnosis, or treatment. Dosing decisions should be confirmed with your doctor, pediatrician, or pharmacist, especially for infants, medically complex children, or anyone taking other medications. In a medical emergency, call emergency services immediately.