Acetaminophen Dose Calculator
Estimate a weight-based acetaminophen (paracetamol) dose and the maximum safe daily amount, with adult single-dose and daily ceilings applied.
How it works
Single dose = min(weight × mg/kg, 1000 mg) · Max daily = min(weight × 75 mg/kg, 4000 mg, single × doses)
Acetaminophen (paracetamol) is dosed at about 10–15 mg/kg per dose, but two hard limits always apply: no single dose above roughly 1,000 mg and no more than 4,000 mg (many clinicians use 3,000 mg) in 24 hours for adults, and no more than 75 mg/kg/day for children. This generic tool applies those ceilings, but the true safe dose depends on age, liver health, alcohol use and — critically — every other product that contains acetaminophen. Because overdose causes serious liver damage, always confirm with a pharmacist or the label.
Worked example
A 20 kg child at 15 mg/kg gets 20 × 15 = 300 mg per dose. Every 6 hours allows 4 doses a day, so 300 × 4 = 1,200 mg, which is under the 20 × 75 = 1,500 mg/kg/day ceiling — the daily maximum shown is 1,200 mg.
Sources: FDA — Acetaminophen information
Frequently asked questions
What is the maximum acetaminophen in a day?
For most adults the label maximum is 4,000 mg in 24 hours, and many clinicians recommend staying at or below 3,000 mg, especially with regular use. For children it is 75 mg/kg/day up to the adult limit. Exceeding these — often by combining products — risks severe liver injury.
Why must I count combination medicines?
Acetaminophen is hidden in many cold, flu and prescription pain products. Doses from every source add up toward the daily maximum, so taking a standalone tablet plus a combination cough remedy can unknowingly push you over the safe limit. Read every label.
Does alcohol or liver disease change the safe dose?
Yes. Regular alcohol use, liver disease, fasting and some medications lower the safe amount because they affect how the liver processes acetaminophen. In these situations the maximum is reduced — a clinician or pharmacist should set the dose.
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Educational estimate only — not medical advice, and not a substitute for a clinician, pharmacist or product label. Dosing, fluid and kidney decisions must be confirmed by a qualified professional using the actual drug, patient and situation. Do not use this tool to self-treat.