If you’ve ever stood in front of a medicine cabinet wondering how much paracetamol to give a child based on weight rather than age, you’re not alone. Official guidelines from the UK’s NHS and Ireland’s HSE both anchor pediatric dosing at 15 mg per kilogram per dose, but converting that number into safe liquid mL can still trip up parents and carers.

4 related posts

Standard dose per kilogram: 15 mg/kg ·
Maximum daily dose: 60 mg/kg (max 4 g for adults) ·
Dosing interval: Every 4–6 hours ·
Minimum age for weight-based dosing: 3 months (or as advised by doctor) ·
Common liquid concentration: 120 mg / 5 mL (children 3 months–6 years) ·
Number of doses per 24 hours: Maximum 4

Quick snapshot

1Confirmed facts
  • Standard pediatric dose: 15 mg/kg per dose (HSE Ireland)
  • Maximum 4 doses per 24 hours for children (NHS UK)
  • Adults ≥50 kg: 500–1000 mg per dose (TGA Australia)
2What’s unclear
  • Exact mg-to-mL conversion varies by brand (some use 250 mg/5 mL for older children) (NHS)
  • Whether weight-based dosing should be used for infants under 3 months without medical advice (NHS restricts to babies over 4 kg born after 37 weeks)
3Timeline signal
  • 1956 — Paracetamol introduced as an analgesic
  • 1990s — Weight-based dosing guidelines become standard for children
  • 2000s — Many countries set max daily dose at 60 mg/kg for children
  • 2010s — Digital dose calculators emerge, reducing calculation errors
4What’s next
  • More mobile-friendly dose calculators integrated into health apps
  • Harmonisation of pediatric dosing charts across UK, Ireland, Australia, and New Zealand
  • Updated MHRA guidance on maximum single dose for low-weight adults

Five key numbers every carer should know at a glance.

Item Value
Standard pediatric dose per kg 15 mg/kg per dose
Maximum daily pediatric dose 60 mg/kg (max 4 doses)
Adult standard dose (≥50 kg) 500–1000 mg every 4–6 hours
Adult maximum daily dose 4000 mg
Liquid concentration (infants/toddlers) 120 mg per 5 mL

How to calculate paracetamol dosage by weight for children?

The core principle, backed by every major health authority, is simple: use the child’s actual weight, not their age, to determine each dose. Australia’s Therapeutic Goods Administration and New Zealand’s bpacnz both anchor dosing on 15 mg per kilogram of body weight.

The upshot

Weight beats age every time — a heavier 3-year-old may need more than a light 5-year-old, and only a scale gives the right answer.

Step 1: Weigh the child

  • Use a digital scale in kilograms. In a pinch, use the most recent clinic weight.
  • For babies under 3 months, the NHS (UK health service) says paracetamol is only suitable if they weigh over 4 kg and were born after 37 weeks.

Step 2: Use the standard dose of 15 mg per kg

Multiply the child’s weight (in kg) by 15 to get the milligram dose. The HSE (Ireland’s health executive) and bpacnz (NZ clinical guideline body) both confirm this formula. Example: a 10 kg child needs 10 × 15 = 150 mg of paracetamol per dose.

Step 3: Convert mg to mL for liquid formulations

Most children’s paracetamol comes as 120 mg per 5 mL. To find the volume: (desired mg ÷ 120) × 5 = mL. For the 10 kg child needing 150 mg: (150 ÷ 120) × 5 = 6.25 mL. If your bottle uses a different concentration (e.g., 250 mg/5 mL for children aged 6 years and older, per HSE chart), adjust the denominator.

Step 4: Confirm maximum daily dose

The NHS and HSE both state the daily ceiling is 60 mg/kg, never more than 4 doses in 24 hours, with at least 4 hours between each dose. For a 10 kg child, that’s 600 mg total per day.

Bottom line: Paracetamol dosing for children is scientifically robust — 15 mg/kg per dose, max 4 doses a day. Parents: invest in a scale and a syringe. Always use the concentration printed on the bottle, not the age band on the box.

What is the paracetamol dose per kg for children in mL?

The most common liquid strength for young children is 120 mg/5 mL. Here’s how that translates into practical volumes for typical weights.

Child weight (kg) Dose (mg) Volume (mL) of 120 mg/5 mL
5 kg 75 mg 3.125 mL
8 kg 120 mg 5 mL
10 kg 150 mg 6.25 mL
15 kg 225 mg 9.375 mL
20 kg 300 mg 12.5 mL

The NHS provides an age-banded chart that roughly aligns with these weights: children aged 6–23 months (typical 8–12 kg) get 5 mL; children 4–5 years (roughly 16–20 kg) get 10 mL. But weight-based calculation is more precise because it accounts for the actual child, not the average.

For children 6 years and older, the HSE switches to 250 mg/5 mL liquid. For a 20 kg child, 15 mg/kg = 300 mg, which is 6 mL of the stronger formulation.

“The dose of paracetamol is based on a child’s weight and not their age.”

— bpacnz (New Zealand clinical guidance)

Bottom line: For 120 mg/5 mL liquid, the conversion formula is (weight × 15) ÷ 120 × 5 = mL. For 250 mg/5 mL, use (weight × 15) ÷ 250 × 5. Always double‑check the concentration on your bottle.

What is the paracetamol dose per kg for adults?

For adults weighing 50 kg or more, the standard dose is 500–1000 mg every 4–6 hours, with a maximum of 4000 mg in 24 hours, per TGA (Australia’s drug regulator). Weight-based calculation isn’t necessary for these individuals because the fixed tablet strengths (500 mg, 1000 mg) fall within the safe 10–15 mg/kg range for typical adult weights.

Standard adult dosing (500 mg or 1000 mg tablets)

  • Adults ≥50 kg: 500–1000 mg per dose, up to 4 times a day.
  • Maximum single dose: 1000 mg.
  • Maximum total daily dose: 4000 mg.

Weight-based dosing for adults under 50 kg

Adults who are underweight or have a low body mass should use the same children’s formula: 15 mg/kg per dose. The NHS advises that adults under 50 kg can use liquid paracetamol (10–20 mL of 120 mg/5 mL up to 4 times a day) or calculate a tablet dose. For example, a 45 kg adult needs 675 mg per dose — that’s one 500 mg tablet plus half a 500 mg tablet.

Why this matters

A single 1000 mg tablet for a 45 kg person gives 22 mg/kg, well above the standard dose. Using weight-based dosing prevents accidental over‑dosing in this group.

Bottom line: Adults ≥50 kg stick with fixed tablets. Adults <50 kg should treat themselves like a child — use 15 mg/kg per dose and never exceed 4000 mg daily.

What is the paracetamol dosage by weight for babies?

Babies under 3 months should only receive paracetamol on medical advice. The NHS specifies that it’s safe for infants aged 2–3 months only if they weigh over 4 kg and were born after 37 weeks of pregnancy. For babies 3 months and older, the standard 15 mg/kg rule applies.

Age and weight considerations

  • Use only infant drops — typically 100 mg/mL (concentrated) or 120 mg/5 mL — with the measuring syringe supplied.
  • Never guess mL from an age band alone. A 6-month-old who weighs 6 kg needs 90 mg (0.9 mL of 100 mg/mL or 3.75 mL of 120 mg/5 mL).

Safe dosing for infants 3–12 months

The HSE chart starts at 2 months with the 120 mg/5 mL concentration. For a 6 kg baby, the dose is 90 mg, which equals 3.75 mL of 120 mg/5 mL. The TGA likewise recommends 15 mg/kg for this age group.

“Babies aged 2 to 3 months can be given paracetamol only if they weigh over 4 kg and were born after 37 weeks of pregnancy.”

— NHS (UK national health service)

Bottom line: For babies 3–12 months, weight is the only reliable guide. Never use a household spoon — always the oral syringe that comes with the medicine.

What is the maximum paracetamol dose for a child per day?

The absolute ceiling is 60 mg/kg per day, divided into no more than four separate doses. This is consistent across the NHS, HSE, TGA, and bpacnz.

Calculating total daily amount

For a 10 kg child: 10 × 60 = 600 mg total per day. At four doses, that’s 150 mg each — consistent with the single-dose calculation. Never give a sixth dose even if the child still has fever.

Signs of overdose

The TGA warns that taking more than one paracetamol-containing product at the same time can be dangerous. Overdose symptoms include nausea, vomiting, and abdominal pain. If your child vomits shortly after a dose, wait the full 4 hours before the next dose.

What to watch

Accidental overdose often happens when a carer gives an extra dose for a lingering fever or combines paracetamol with a cold medicine that already contains it. Check all labels.

Bottom line: 60 mg/kg per day is the hard stop. If a child needs more than four doses in 24 hours, call a doctor — never exceed the ceiling.

Clarity: confirmed facts & what remains unclear

Confirmed facts

  • 15 mg/kg is the standard dose for children (HSE, NHS).
  • Maximum 4 doses per 24 hours for children (NHS).
  • Adults ≥50 kg: 500–1000 mg per dose (TGA).
  • Babies 2–3 months only on medical advice, weight >4 kg, born at term (NHS).

What’s unclear

  • Exact mg-to-mL conversion for all liquid brands (some use 250 mg/5 mL).
  • Whether weight-based dosing should be used for infants under 3 months without medical advice.
  • Whether the HSE weight-based chart always matches product packaging (HSE notes discrepancy).

Expert perspectives on safe dosing

“The dose of paracetamol is based on a child’s weight and not their age.”

— bpacnz (New Zealand clinical guidance body)

“Weight-based dosing for Paracetamol in children uses 15 mg/kg/dose.”

— HSE (Ireland’s Health Service Executive)

“Taking more than one medicine containing paracetamol at the same time can be dangerous.”

— TGA (Australian Therapeutic Goods Administration)

“Paracetamol can be given to children aged 3 months and over up to 4 times a day, with at least 4 hours between doses.”

— NHS (UK national health service)

The pattern from four authoritative sources is identical — weight-based dosing at 15 mg/kg is the global gold standard, but the precise liquid volume and the age floor for infants carry small variations that carers must check locally.

Summary

Paracetamol is one of the safest analgesics when dosed correctly by weight, but the margin for error narrows with young children and low-weight adults. For parents in Ireland and the UK relying on HSE and NHS guidance, the choice is clear: use a scale, follow the mg/kg formula, never exceed four doses daily, and always read the concentration on the bottle — because even a single incorrect mL can tip the balance from therapy to risk.

Additional sources

vinmec.com, pmc.ncbi.nlm.nih.gov, gov.uk

Understanding how to calculate the correct dose by weight is essential, but parents should also be aware of safe paracetamol dosing frequency to avoid accidental overdose.

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Frequently asked questions

Can I give paracetamol to a baby under 3 months?

Only on medical advice. The NHS allows it for babies 2–3 months if they weigh over 4 kg and were born at full term. Always check with your doctor first.

What if my child refuses liquid paracetamol?

Try mixing the measured dose with a small amount of milk, juice, or yoghurt — but not the child’s entire bottle, in case they don’t finish it.

How do I measure the correct mL dose?

Use the oral syringe that comes with the medicine. Hold the syringe at eye level to check the line. Never use a kitchen teaspoon — volumes vary wildly.

Can I use a household teaspoon for measuring?

No. A typical teaspoon holds anywhere from 3 to 6 mL. Always use the dosing device supplied with the medication.

Is it safe to alternate paracetamol with ibuprofen?

Some guidelines allow it (e.g., for fever unresponsive to one drug), but alternate at different times and track both cumulative doses. Ask your GP or pharmacist first.

What should I do if I accidentally give too much paracetamol?

Contact your doctor or go to the emergency department immediately. Even if the child seems fine, paracetamol overdose can cause delayed liver damage.

Does the dosage change if the child has a fever?

No. The dose remains 15 mg/kg regardless of fever severity. Fever does not increase the maximum safe dose.

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