Children's Motrin / Ibuprofen dose calculator

The math: 10 mg per kg, every 6 to 8 hours

Pediatric ibuprofen dosing is 10 milligrams per kilogram of body weight per dose, with a range of 5 to 10 mg/kg for mild fever or pain. Doses repeat every 6 to 8 hours as needed, with a maximum of 4 doses in 24 hours and a daily ceiling of 40 mg per kg. Most pediatricians dose at the 10 mg/kg ceiling because it works better and the safety margin is wide; some use 5 mg/kg for routine teething or mild discomfort. A 25-pound child (about 11.3 kg) at 10 mg/kg is 113 mg — that's 5.7 mL of Children's liquid (100 mg per 5 mL). The bottle's age chart often suggests 5 mL flat for this weight band, which under-doses about a quarter of kids in that band.

Compared to Tylenol: ibuprofen lasts longer per dose (6 to 8 hours versus 4 to 6 for acetaminophen) and is anti-inflammatory, which makes it the better choice for teething pain, ear infections, sore throats, and post-vaccination soreness. Acetaminophen has none of that anti-inflammatory action and is gentler on the stomach, which is why it's the standby for routine fever and for kids under 6 months. Both are equally effective at reducing the temperature itself.

The two pediatric formulations parents constantly confuse

Two liquid ibuprofen products sit next to each other in every pharmacy aisle:

• Infants' Drops: 50 mg per 1.25 mL. Concentrated. Comes with a 1.25 mL syringe. Designed for babies 6 to 23 months where small volumes matter.
• Children's Liquid: 100 mg per 5 mL. Diluted. Comes with a 5 mL cup or syringe. The default for kids 2 years and up.

The concentration is roughly double in the infants' drops on a per-mL basis. Giving 5 mL of the infants' drops thinking it's the children's strength is a 4x overdose. Always check the milligrams per milliliter on the label every single dose. If you only have one of the two formulations on hand, the calculator below adjusts the volume — but it cannot tell which bottle is in your kitchen. Look at the label, not the box color.

Why food matters for ibuprofen (and not Tylenol)

Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID). NSAIDs block prostaglandins, which is how they reduce inflammation, but those same prostaglandins protect the stomach lining. On an empty stomach, ibuprofen can irritate or, in rare cases with long-term use, cause bleeding. The fix is simple: give it with food, milk, or at least a glass of water and a small snack. This isn't a strict rule for a single dose during a fever, but it matters for kids who get ibuprofen frequently for sports injuries or chronic headaches.

Two other ibuprofen-specific considerations. First, dehydration plus ibuprofen is a kidney risk — if your child is vomiting, has diarrhea, or hasn't peed in 8+ hours, switch to Tylenol until they're rehydrated. Second, kids with asthma sometimes flare on NSAIDs (about 1 in 20). If wheezing starts within an hour of a dose, stop and call your pediatrician. The rest of the time, kidney function in healthy children handles ibuprofen without trouble.

Alternating Tylenol and Motrin safely

For persistent fever that breaks through one medication, pediatricians often recommend alternating. The schedule that works:

• Give Tylenol at hour 0
• Give Motrin at hour 3 (3 hours later)
• Give Tylenol at hour 6
• Give Motrin at hour 9
• Repeat — never giving either drug more often than its own schedule (Tylenol every 6, Motrin every 8)

The benefit: continuous fever and pain control without exceeding either drug's daily cap. The risk: a tired parent loses track and double-doses one of the two. Always write down each dose with time and which drug — phone notes app, sticky note, anywhere visible. Alternating works well for short bursts (24 to 48 hours of fever). Past that point, the fever needs a doctor's eye, not more rotation.

How to use this calculator

Enter weight in pounds or kilograms, pick the age band, and tell the tool which ibuprofen product you have. The output is the exact dose in mL or tablets, the schedule, and the daily cap for that weight. If you have both Infants' Drops and Children's Liquid in the house, the calculator will show whichever you select — but use the Children's Liquid if your child is over 24 months. The smaller-volume Infants' Drops are designed for tiny doses, and giving the volume needed for a 30-pound kid would be three full syringes. Tape a sticky note to the bottle with the calculated dose and your child's weight so a partner or grandparent doesn't have to redo the math at 3 a.m.

When to call your pediatrician (and when to call 911)

Call your pediatrician same-day for fever over 104°F at any age, fever lasting more than 3 days, ear pain that doesn't improve in 48 hours, persistent vomiting after an ibuprofen dose, hives or facial swelling after a dose, dark or blood-tinged urine, or any new wheezing. Call 911 or go to the ER for any baby under 3 months with a rectal temperature of 100.4°F or higher (do not use ibuprofen at all under 6 months), severe stomach pain that won't ease, signs of bleeding (black or bloody stools, vomit that looks like coffee grounds), trouble breathing, severe lethargy, stiff neck, a seizure with the fever, or a rash that doesn't blanch when you press a glass on it. Ibuprofen masks the fever; it does not treat the cause. If the cause is serious, the calculator's job stops and the doctor's job starts. This calculator gives general pediatric dosing guidance based on AAP recommendations. For any concern about your specific child, call your pediatrician or 911 if it is an emergency.