Pediatric Dose Calculator
Work out a weight-based paediatric dose with every step shown: mg/kg × weight, the volume for a chosen concentration, the 24-hour total with its ceiling, and maintenance fluids by both the 4-2-1 rule and Holliday–Segar.
Educational reference only.
This calculator does not prescribe. Doses here are common textbook examples and vary between countries, hospitals and indications. Always follow your local formulary and a prescriber’s instructions, check allergies, weight, renal and hepatic function, and have a second person verify every calculation before a medicine is given. If a child is critically unwell, use your resuscitation and formulary resources, not this page.
1. Patient
Accepted range 0.5–120 kg. A measured weight is always better than an estimate.
Working weight: 12 kg (entered)
Used exactly as entered.
2. Medicine
- Dose
- 15 mg/kg
- Route
- oral
- Max single
- 1000 mg
- Max 24 h
- 4000 mg
- 60 mg/kg/day
Frequency: every 4–6 hours, max 4 doses in 24 h.
Use 60 mg/kg/day as the ceiling (the absolute adult cap is usually 4 g). Check for paracetamol in combination products before giving a second source.
3. Dose
Per dose
180 mg
12 kg × 15 mg/kg = 180 mg
Volume to draw up
7.5 mL
180 mg ÷ 24 mg/mL = 7.5 mL
24-hour total
720 mg per day
180 mg × 4 doses = 720 mg/day · effective ceiling 720 mg/day
4. Maintenance fluids
4-2-1 rule (hourly)
44 mL/hour
- 10 kg × 4 mL/kg/h = 40 mL/h
- 2 kg × 2 mL/kg/h = 4 mL/h
4 mL/kg/h for the first 10 kg, 2 mL/kg/h for the next 10 kg, 1 mL/kg/h for each kilogram above 20 kg.
Holliday–Segar (24 hours)
1100 mL/day
- 10 kg × 100 mL/kg/day = 1000 mL/day
- 2 kg × 50 mL/kg/day = 100 mL/day
That is 45.8 mL/h averaged over the day. The two rules agree closely up to about 20 kg and drift apart above it, because the 4-2-1 rule is written for children; adult maintenance is usually capped near 2.5 L a day.
Maintenance fluids are for a euvolaemic child who cannot drink. They are not resuscitation: a fluid bolus is 10–20 mL/kg of an isotonic crystalloid given rapidly and reassessed. Many guidelines now recommend isotonic maintenance fluid with glucose, and extra care in meningitis, head injury, cardiac and renal disease. The 20 mL/kg enteric-loss replacement for this child would be 240 mL per replacement volume.
About this tool
Pediatric Dose Calculator multiplies a weight by a standard mg/kg figure, converts the result to a volume for the concentration you select, totals the 24-hour dose against a reference ceiling and adds maintenance fluids by the 4-2-1 rule and the Holliday–Segar method, showing the arithmetic at every step. The drug table holds eight common weight-based medicines as worked examples; it is not a formulary. The APLS weight estimate is a formula, not a measurement. Everything is computed in your browser and nothing you type is stored or sent anywhere — but the output is a reference, not a prescription.
- 100% free — no account needed
- Runs in your browser
- Nothing is uploaded
Frequently asked questions
Is Pediatric Dose Calculator really free?
Yes. Pediatric Dose Calculator is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.
Does Pediatric Dose Calculator upload my data?
No. Pediatric Dose Calculator runs entirely inside your browser, so anything you type, paste, or open stays on your own device.
Do I need to sign up or install anything?
Neither. There is no account and nothing to download — open the page and Pediatric Dose Calculator is ready to use on desktop or mobile.
Does Pediatric Dose Calculator work offline?
Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.
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