Paracetamol Pediatric
Calculator

Paracetamol (acetaminophen) is the most widely used analgesic and antipyretic in children globally. Available without prescription in most countries, it is administered by millions of caregivers daily — making accurate dosing knowledge one of the most impactful aspects of pediatric medication safety.

Despite its ubiquity, paracetamol toxicity from unintentional double-dosing — often combining a plain paracetamol product with a paracetamol-containing combination cold or flu remedy — remains one of the leading causes of acute liver failure in children in high-income countries.

This calculator uses the child's actual weight rather than age-based dosing tables, which is the clinically recommended approach. Age-based dosing systematically underdoses large children and overdoses small ones — weight-based dosing eliminates this systematic error.

Enter the child's weight (in kg, g, or lb), age (for age-appropriateness warnings), select the formulation, and optionally adjust the mg/kg dose rate (default 15 mg/kg), maximum single dose, daily dose cap, and dosing interval.

The tool returns the single dose in mg, the volume of suspension in mL (for liquid formulations), the maximum daily dose, and a colour-coded alert if the calculated dose approaches or exceeds the adult cap.

Inline field validation prevents clinically implausible entries — weights over 150 kg or negative values, mg/kg inputs outside the expected 10–15 mg/kg range, or intervals shorter than 4 hours all generate visible inline error messages rather than silently generating potentially unsafe results.

A rounding control snaps the mL result to the nearest 0.5 mL, aligning with standard oral syringe calibrations. For small infants, finer rounding (0.1 mL) is available.

Session history tracks all calculations for the session with timestamps, supporting review of multiple patients in a clinical session and export to CSV for documentation.

The standard dose is 10–15 mg/kg per dose, given every 4–6 hours. The calculator defaults to 15 mg/kg, which sits at the top of the recommended range and is appropriate for most clinical situations. For mild discomfort or maintenance analgesia, 10 mg/kg provides adequate coverage with a wider safety margin.

The maximum single dose is 1,000 mg (1 g) — this is the standard adult cap that applies from approximately 67 kg upwards. For children below this weight, the weight-based dose will be lower than the adult cap.

The maximum daily dose is 4,000 mg (4 g/day), or approximately 75 mg/kg/day (whichever is lower). This ceiling applies to the total paracetamol from all sources — not just this product. Hepatic impairment, malnutrition, or chronic alcohol use reduces the safe daily ceiling.

Minimum dosing interval is 4 hours, with a maximum of 4 doses per day (every 6 hours is the most common clinical schedule). More frequent dosing risks accumulation and hepatotoxicity.

Syrup 120 mg/5 mL: The standard concentration in many countries, including the UK and parts of Asia. Sometimes labelled as Calpol Infant or equivalent brands. Suitable for infants and young children.

Syrup 250 mg/5 mL: A stronger concentration more suitable for older children and those requiring larger doses. Reducing the volume required for each dose improves palatability and compliance.

Tablet 500 mg: Standard for children and adults who can swallow tablets (typically from around 8–10 years). Half-tablets (250 mg) are practical for children in the 17–35 kg range.

Concentrated drops (100 mg/mL): Very high concentration drops designed for neonates and infants. The small volumes involved require precise measurement with a calibrated dropper — the calculator provides the dose in mg only for this formulation, as dropper calibration varies by product.

Always confirm the concentration printed on the bottle before drawing up a dose. Using the wrong concentration is a common error — a caregiver using 250 mg/5 mL suspension for a dose calculated for 120 mg/5 mL suspension will deliver more than double the intended dose.

Acute paracetamol overdose in children is often initially asymptomatic — early symptoms (nausea, vomiting, abdominal pain) may be mild or absent in the first 24 hours, even with toxic doses. This makes it easy to underestimate the severity of the ingestion.

Hepatotoxicity, which is the primary organ toxicity, typically manifests between 24–72 hours after ingestion. At this stage, transaminases rise and the child may develop jaundice, coagulopathy, and encephalopathy — by which time the window for most effective antidote therapy may have passed.

If an overdose is suspected, contact a Poison Control Centre or take the child to an emergency department immediately — even if the child appears well. The threshold for treatment with N-acetylcysteine (NAC) is age- and weight-specific and must be assessed by a clinician using the Rumack–Matthew nomogram.