π Paracetamol Dosage Calculator
Weight-based acetaminophen dosing with safety limits.
For informational purposes only, not medical advice. Consult a healthcare professional.
Paracetamol, called acetaminophen in the US, is dosed by weight in children and capped by daily totals in adults. The standard single dose is 10 to 15 mg per kilogram of body weight every 4 to 6 hours, with a daily ceiling of 75 mg per kg in children and 4,000 mg in most adults. It is also the most common cause of acute liver failure in overdose, usually from accidentally stacking multiple products that each contain it. This calculator gives weight-based doses with the safety ceilings, for information only: confirm every dose with a clinician or pharmacist.
How to Use This Calculator
Enter the weight in kilograms and pick the age group. The calculator gives the single-dose range, how often it can repeat, and the ceiling for the whole day.
Weigh the person if possible. Guessed weights are the most common source of dosing errors in children, so a bathroom scale beats a memory.
Read the single-dose range of 10 to 15 mg per kg. Most parents aim mid-range; the top of the range is for higher fevers, not routine use.
Check the maximum daily total before repeating doses through the night. The day ceiling is where liver safety lives, and combination cold medicines often hide extra paracetamol.
How the Math Works
Multiply weight in kilograms by 10 and by 15 to get the single-dose range. A 20 kg child gets 200 to 300 mg per dose. The interval is every 4 to 6 hours as needed, with no more than 5 doses in 24 hours for children. The daily maximum is 75 mg per kg for children, which for the 20 kg child is 1,500 mg, while adults cap at 4,000 mg per 24 hours, lower at 3,000 mg for many clinicians in patients with liver disease, heavy alcohol use, or frailty. Adult single doses run 325 to 1,000 mg regardless of weight, since the flat adult dosing already assumes adult body mass.
Worked Example
A 20 kg child with fever gets a single-dose range of 200 to 300 mg of paracetamol, repeatable every 4 to 6 hours, with a full-day ceiling of 1,500 mg. In practice that means a 240 mg spoonful of liquid sits comfortably inside the range, while giving doses every 3 hours through the night would break the interval rule even before hitting the daily cap. The calculator shows both limits because the interval and the ceiling fail independently.
Reading Your Result
Stay inside both the single-dose range and the daily maximum; satisfying one while breaking the other is still an overdose pattern. For children, the 15 mg per kg end of the range is for higher fevers, not the default. For adults, 1,000 mg per dose up to four times daily is the standard ceiling, and anyone with liver disease, daily alcohol use, or low body weight should treat 3,000 mg as the practical max and confirm with their clinician. If pain or fever needs the maximum dose around the clock for more than a few days, that persistence itself deserves medical review.
| Group | Single dose | Interval | Daily max |
|---|---|---|---|
| Child | 10-15 mg/kg | Every 4-6 hours | 75 mg/kg |
| Adult | 325-1000 mg | Every 4-6 hours | 4000 mg |
| Adult, liver risk | 325-650 mg | Every 6-8 hours | 3000 mg |
Limitations
This tool cannot see the paracetamol hiding in combination cold, flu, and prescription pain products, which is the classic accidental-overdose route: always total every source. It does not adjust for liver disease, chronic alcohol use, or malnutrition, all of which lower the safe ceiling. Dosing infants under 3 months needs a clinician, not a calculator, and any suspected overdose needs emergency care immediately, since the antidote works best within hours.
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Related tools: pediatric dose calculator prescription refill date calculator BMI calculator.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
Is paracetamol the same as acetaminophen?
Yes, exactly the same drug. Paracetamol is the name used in the UK, Europe, and most of the world; acetaminophen is the US name, sold as Tylenol. Dosing, risks, and maximums are identical. If a label says either name, it counts toward the same daily total.
How do I dose paracetamol for a child?
By weight: 10 to 15 mg per kilogram per dose, every 4 to 6 hours as needed, maxing out at 75 mg per kg per day. A kitchen spoon is not a measuring device; use the syringe or cup that came with the medicine. When in doubt, the pharmacist will do the math with you in under a minute.
What is the maximum paracetamol per day for adults?
4,000 mg in 24 hours for healthy adults, which is eight extra-strength 500 mg tablets. Many clinicians advise 3,000 mg as the practical ceiling for older adults, people with liver disease, or regular heavy drinkers. The liver injury risk climbs steeply above these totals.
Can I alternate paracetamol and ibuprofen?
Many pediatricians suggest it for stubborn fevers, but it doubles the bookkeeping and the error rate. If you do, write down every dose with the time and drug, because the two medicines have different intervals and maximums. Never exceed either drug ceiling in the confusion.
Why is paracetamol dangerous in overdose?
The liver converts a small fraction of each dose into a toxic byproduct that glutathione normally neutralizes. In overdose, glutathione runs out and the byproduct destroys liver cells. The frightening part is the delay: people feel fine for the first day while the damage progresses, which is why suspected overdoses need emergency care immediately.
Does paracetamol in cold medicine count?
Absolutely, and this is the most common accidental overdose. Multi-symptom cold and flu products, many prescription painkillers, and sleep aids frequently contain 325 to 500 mg per dose. Add up every source before taking more, or choose single-ingredient products so the math stays visible.
How soon does paracetamol start working?
Typically 30 to 60 minutes for pain and fever, peaking around 2 hours. If there is no effect after an hour at a proper weight-based dose, the problem may need a different approach rather than a bigger dose. Redosing early because it has not kicked in yet is a classic error.
Can I take paracetamol on an empty stomach?
Yes. Unlike ibuprofen, paracetamol does not irritate the stomach lining and works fine without food. A glass of water is enough. Chronic alcohol use is the real interaction to worry about, not meal timing.
Is it safe in pregnancy?
It is generally considered the pain and fever reliever of choice in pregnancy when needed, used at the lowest effective dose for the shortest time. Ibuprofen and other NSAIDs are the ones usually avoided, especially later in pregnancy. Confirm with your obstetrician for your situation.
What should I do in a suspected overdose?
Go to emergency care immediately, even if the person feels fine. The antidote, N-acetylcysteine, is highly effective within 8 hours and still useful later, but every hour matters. Bring every medicine bottle so the team can total the dose, and call poison control on the way.