Paracetamol Dosage Calculator
Enter the patient weight and select the formulation to get the recommended single dose in milligrams, the maximum safe single dose, the daily dose limit, and (for liquid medicines) the exact volume to measure. Results update instantly as you type. This tool covers children from 3 months and adults, and supports metric and imperial weights.
How paracetamol dosing works
Paracetamol (also called acetaminophen) is dosed by body weight for children and by a fixed amount for adults. For children the standard single dose is 15 milligrams per kilogram of body weight, given every 4 to 6 hours as needed, up to a maximum of 4 doses in any 24-hour period. The upper safe limit for any single child dose is 20 mg/kg, and the total amount given in a day should not exceed 60 mg/kg. For adults and adolescents aged 13 and over who weigh at least 50 kg, the standard single dose is 500 mg to 1000 mg, with a daily ceiling of 4000 mg for short-term use. Body weight matters more than age here: anyone under 50 kg, including many 13 to 15 year olds and smaller adults, should be dosed by weight at 15 mg/kg per dose with a 24-hour total of no more than 60 mg/kg and never above 3000 mg. Anyone with liver disease, chronic malnutrition, dehydration, or a history of heavy alcohol use should keep their daily total below 2000 mg and consult a doctor before using paracetamol regularly.
Liquid volume formula and how to measure accurately
When using an oral liquid (syrup or suspension), you need to convert the milligram dose into a volume in millilitres. The formula is: volume (ml) = (5 ml / concentration per 5 ml) x dose in mg. For example, if you have a 120 mg/5 ml suspension and the dose is 180 mg, the volume is (5 / 120) x 180 = 7.5 ml. Always use an oral dosing syringe rather than a kitchen teaspoon. Kitchen spoons can hold anywhere from 2.5 ml to 7 ml and do not give an accurate dose. Oral syringes are marked in 0.5 ml or 1 ml increments and are available free from most pharmacies. Shake the bottle before each use if the label says to do so, as the active ingredient can settle.
Common formulations and their concentrations
Paracetamol is sold in many strengths and forms. Infant and children oral suspension in many markets is 120 mg per 5 ml or 160 mg per 5 ml. Older-child and adult syrups are often 250 mg per 5 ml. Standard tablets and capsules are 500 mg each, and many adult combination cold-and-flu products contain 325 mg or 500 mg per tablet. Always check the label of the exact product you have before calculating a dose, as the concentration varies widely. This calculator lets you choose from the most common liquid concentrations so the volume calculation matches your bottle.
Safety: maximum doses and overdose risk
Paracetamol is safe at the recommended dose but can cause serious, sometimes fatal, liver damage in overdose. The risk is greatest when multiple products containing paracetamol are used at the same time, for example a pain tablet and a cold-and-flu capsule. Always check that no other product you are taking also contains paracetamol. Children who are malnourished, have liver disease, or are taking enzyme-inducing medicines (such as some anti-epileptics) may be at higher risk of toxicity at normal doses. If an accidental overdose is suspected, seek emergency medical attention immediately even if the child or adult seems well, as symptoms of liver injury may not appear for 24 to 72 hours.
Paracetamol dosing reference by patient type
| Patient | Recommended dose | Maximum single dose | Maximum daily dose | Notes |
|---|---|---|---|---|
| Child (3-12 months) | 10-15 mg/kg | 20 mg/kg | 60 mg/kg/day | Use liquid; medical review for under 3 months |
| Child (1-5 years) | 10-15 mg/kg | 20 mg/kg | 60 mg/kg/day | Liquid or chewable preferred |
| Child (6-12 years) | 10-15 mg/kg | 20 mg/kg | 60 mg/kg/day | Tablet or liquid |
| Adult / adolescent under 50 kg | 15 mg/kg | 15 mg/kg | 60 mg/kg/day (max 3000 mg) | Flat adult doses are too high below 50 kg |
| Adult (13+ years, 50 kg and over) | 500-1000 mg | 1000 mg | 4000 mg/day | Reduce to 2000 mg/day for regular/chronic use |
| Adult (liver disease) | 500 mg | 500 mg | 2000 mg/day | Consult a doctor before use |
Based on WHO guidelines and BNF for Children. Child doses are weight-based; adult doses are fixed. Always leave at least 4 hours between doses.
Frequently asked questions
How do I calculate the paracetamol dose for a child by weight?
Multiply the child weight in kilograms by 15 to get the recommended single dose in milligrams. For example, a 20 kg child: 20 x 15 = 300 mg per dose. This can be given every 4 to 6 hours, up to 4 times a day. Never give more than 20 mg/kg in a single dose or 60 mg/kg in a day.
How much liquid paracetamol suspension should I give?
Divide the dose in mg by the concentration per ml of your suspension, then multiply by 5. If your suspension is 120 mg per 5 ml and the dose is 180 mg: (5 / 120) x 180 = 7.5 ml. Always measure with an oral dosing syringe, not a kitchen spoon.
What is the maximum paracetamol dose for an adult?
Adults weighing 50 kg or more can take up to 1000 mg (two standard 500 mg tablets) per dose and no more than 4000 mg in 24 hours for short-term use. Below 50 kg the flat adult dose is too high: use 15 mg/kg per dose with a daily total of no more than 60 mg/kg and never above 3000 mg. If you take paracetamol regularly, have liver disease, or drink alcohol regularly, keep the daily total to 2000 mg or less.
Can I give paracetamol to a baby under 3 months?
Paracetamol is generally not recommended for babies under 3 months without medical supervision. If your baby is under 3 months and in pain or has a fever, contact your doctor or a paediatric nurse before giving any paracetamol.
How long should I leave between paracetamol doses?
Always leave at least 4 hours between doses. You can give up to 4 doses in 24 hours, which works out to every 6 hours. If pain or fever is not controlled by the maximum dose frequency, see a healthcare professional rather than increasing the dose.
Is paracetamol the same as acetaminophen?
Yes. Paracetamol and acetaminophen are the same active ingredient: the international non-proprietary name is paracetamol and it is sold as acetaminophen in the United States and Canada. Brand names include Tylenol, Panadol, Calpol and many others. The dosing recommendations in this calculator apply to both.