How this instrument works
This tool takes a child's age band, from 3 months up to 5 years old, and applies the fixed dose the NHS (sourced from the BNF for Children) sets for that band using the standard 120 mg/5 mL infant paracetamol liquid sold across the UK. Unlike this site's tylenol-dosage calculator, which follows the US FDA's weight-based mg/kg convention, UK guidance for this specific liquid is dosed by age band rather than by weight — so the two calculators will not agree with each other, and neither substitutes for the other.
Each age band has one fixed milligram dose, converted here to millilitres of the 120 mg/5 mL liquid, repeated up to four times in 24 hours with at least 4 hours between doses. A baby 3-5 months old gets 60 mg (2.5 mL) per dose; 6-23 months gets 120 mg (5 mL); 2-3 years gets 180 mg (7.5 mL); and 4-5 years gets 240 mg (10 mL) — each capped at a 24-hour maximum of four doses.
This calculator is scoped strictly to children under 6 years old using the 120 mg/5 mL infant liquid. Children aged 6 and older move to a different, more concentrated 250 mg/5 mL liquid or to tablets, each with its own separate NHS dosing bands that this calculator does not cover — it should not be used, and does not apply, to a child 6 or older. Always confirm the dose with a pharmacist or GP first, especially for a baby under 3 months old, who needs individual medical advice rather than an age-band figure, and measure only with the plastic dosing syringe or spoon that comes with the medicine, never a kitchen spoon.
- Select the child's age band from 3-5 months, 6-23 months, 2-3 years, or 4-5 years.
- Read the dose in milligrams for that age band.
- Read the same dose converted to millilitres of the 120mg/5mL infant liquid.
- Check the 24-hour maximum in mg before giving a second, third, or fourth dose.
- Leave at least 4 hours between doses, and confirm with a pharmacist or GP before the first dose.
Worked example — 6-23 months and 4-5 years
A baby aged 6-23 months takes the 120 mg dose for that band. Converted to the 120 mg/5 mL liquid, that's 120 ÷ 120 × 5 = 5 mL per dose — a full 5 mL syringe. Up to four doses in 24 hours, each at least 4 hours apart, gives a daily maximum of 120 × 4 = 480 mg.
A child aged 4-5 years takes the 240 mg dose for that band, which works out to 240 ÷ 120 × 5 = 10 mL of the same 120 mg/5 mL liquid per dose — double the 6-23 month volume, reflecting the larger fixed dose for that band. Four doses in 24 hours caps the daily total at 240 × 4 = 960 mg. Both figures assume the 120 mg/5 mL infant liquid; a child this age given the more concentrated 250 mg/5 mL liquid instead would need a different, smaller volume not calculated here.
Questions
Why does this calculator use age instead of weight?
Because that is how UK guidance doses this specific product. The NHS, sourced from the BNF for Children, sets a fixed dose per age band for the standard 120 mg/5 mL infant paracetamol liquid, rather than scaling by kilogram the way the US FDA's guidance does for its own children's acetaminophen products. If a child's weight is unusually low or high for their age, a pharmacist or GP can advise whether the age-band dose still applies.
Does this calculator cover children 6 and older?
No. It is scoped to children aged 3 months to 5 years using the 120 mg/5 mL infant liquid. Children 6 and older use a different, more concentrated 250 mg/5 mL liquid or paracetamol tablets, each with its own separate NHS dosing bands not included here — using this calculator's figures for an older child's different product would give the wrong volume.
Is this the same as the site's Tylenol dosing calculator?
No, and the two will not give matching numbers. The Tylenol dosing calculator on this site follows the US FDA's weight-based mg/kg convention for US children's acetaminophen products. This calculator follows the UK NHS/BNF for Children age-band convention for the UK's 120 mg/5 mL infant liquid — a different dosing system for a different product, not an alternate way of calculating the same dose.
What if my baby is under 3 months old?
This calculator does not cover babies under 3 months. Paracetamol dosing at that age needs individual assessment by a GP, health visitor, or pharmacist rather than a fixed age-band figure — do not extrapolate downward from the 3-5 month band.
How often can doses be repeated, and what if I think too much was given?
Up to four doses in 24 hours, with at least 4 hours between each one. If you think a child has had too much paracetamol, or you're unsure about a dose already given, contact NHS 111, the National Poisons Information Service, or a GP straight away rather than waiting to see if symptoms appear.
Can I measure a dose with a kitchen spoon?
No — use only the plastic oral syringe or measuring spoon that comes with the medicine. Kitchen spoons vary widely in actual volume and are a well-documented source of caregiver dosing errors; if the syringe that came with the bottle is lost, a pharmacist can supply a replacement.
What source is this dosing based on?
The age bands, milligram doses, and 24-hour maximum come from the BNF for Children's paracetamol oral dosing guidance for the 120 mg/5 mL infant suspension, as reflected in NHS medicines information for parents and caregivers.
References
- NHS — Paracetamol for children: age-banded dosing for infant liquid
- Medicines for Children — Paracetamol for mild-to-moderate pain
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.