Calculators

Health calculators

Quick, general-purpose calculators. These are guides only — always check with your pharmacist, doctor or midwife for advice specific to you or your child.

15 kg
225 mg
= 9.4 mL of 120 mg/5 mL liquid, given every 4–6 hours
Daily maximum: 900 mg (60 mg/kg/day) in 24 hours, in no more than 4 doses
Before giving paracetamol: Do not give to babies under 1 month. For babies 1–3 months, check with a doctor or pharmacist first. Never exceed 4 doses in 24 hours or the daily maximum. Do not give if your child has already had a paracetamol-containing product (e.g. a cold and flu remedy) in the last 4–6 hours.
Standard dose: 15 mg/kg per dose (max 1000 mg/dose), every 4–6 hours, max 60 mg/kg or 4000 mg per day — whichever is lower. Source: New Zealand Formulary for Children.
15 kg
75 mg
= 3.75 mL of 100 mg/5 mL liquid, every 6–8 hours
Daily maximum: 600 mg in 24 hours
Before giving ibuprofen: Do not give to babies under 3 months, or to any child who is dehydrated, has asthma triggered by NSAIDs, or has had a reaction to ibuprofen or aspirin before. Give with food. Check with your pharmacist if your child is unwell with vomiting or diarrhoea.
Dose range: 5–10 mg/kg per dose (max 400 mg/dose), every 6–8 hours, max 40 mg/kg/day up to 1.6 g/day. Source: New Zealand Formulary for Children.
75 kg
170 cm
26.0
Body Mass Index
Overweight
BMI is a screening guide, not a diagnosis. It doesn't distinguish muscle from fat, so it can be misleading for athletes, very muscular people, and older adults. It isn't valid for children/teens, or during pregnancy. Some evidence suggests lower BMI thresholds may better reflect health risk for people of Asian ethnicity — ask your pharmacist or GP for a fuller picture, including waist circumference.
Underweight: below 18.5  ·  Healthy weight: 18.5–24.9  ·  Overweight: 25–29.9  ·  Obese: 30 and above. Categories per World Health Organization / NZ Ministry of Health, for adults aged 18–70.
28 days
This is an estimate only. Only around 1 in 20 babies arrive on their exact due date. If a scan has given you a different due date, go with the scan — it's usually more accurate than LMP-based dating, especially if your cycles are irregular.
Calculated using Naegele's rule (LMP + 280 days), adjusted for cycle length. For guidance only — confirm dates with your midwife, doctor or an early scan.
These tools are general guides only and do not replace advice from your pharmacist, doctor or midwife.