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Paediatric Dose Calculation Pathway
Combine current weight, mg/kg wording, supplied dose-range checks and the final dose-to-volume step in one explicit chain.
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Paediatric Calculations
Bring weight-based paediatric medication maths and maintenance fluids together without hiding the intermediate checks.
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Paediatric Dose Calculation Pathway
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Paediatric Maintenance Fluids
Calculate common 4-2-1 hourly and 100-50-20 daily full-maintenance estimates while keeping formula arithmetic separate from clinical prescribing.
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What each Paediatric Calculations lesson teaches
A short recap of every lesson in this topic: the key idea, a worked example and the mistake students make most often. Open any lesson for the full step-by-step teaching and its four levels of practice.
Paediatric Dose Calculation PathwayA paediatric dose calculation is a chain rather than a single sum: weight gives the dose, the supplied range checks it, and the concentration turns it into a volume. Keeping the intermediate values visible is what makes each link checkable.
A paediatric dose calculation is a chain rather than a single sum: weight gives the dose, the supplied range checks it, and the concentration turns it into a volume. Keeping the intermediate values visible is what makes each link checkable.
Formula
dose = dose per kg × weight · volume = dose ÷ concentration
Worked example
A supplied dose of 15 mg/kg for a child weighing 12 kg, from a liquid labelled 120 mg in 5 mL.
- 1Dose: 15 × 12 = 180 mg
- 2Concentration: 120 ÷ 5 = 24 mg/mL
- 3Volume: 180 ÷ 24 = 7.5
180 mg, given as 7.5 mL
Common mistake
Collapsing the chain into one long expression. Writing the dose down before converting it to a volume makes an error visible at the step where it happened.
Show every intermediate value — a paediatric calculation is checked link by link.
Paediatric Maintenance FluidsMaintenance fluid estimates apply different rates to successive weight bands rather than one rate to the whole weight. The bands are supplied by the rule the question specifies, and the results are added together.
Maintenance fluid estimates apply different rates to successive weight bands rather than one rate to the whole weight. The bands are supplied by the rule the question specifies, and the results are added together.
Formula
total = (rate for band 1 × kg in band 1) + (rate for band 2 × kg in band 2) + …
Worked example
A 24 kg child, using the supplied 100/50/20 daily rule.
- 1First 10 kg at 100 mL/kg: 10 × 100 = 1000 mL
- 2Next 10 kg at 50 mL/kg: 10 × 50 = 500 mL
- 3Remaining 4 kg at 20 mL/kg: 4 × 20 = 80 mL
- 4Add the bands: 1000 + 500 + 80 = 1580
1580 mL per day
Common mistake
Applying the first band's rate to the entire weight. Each band covers only the kilograms that fall inside it.
Split the weight into bands, calculate each separately, then add — and state which rule the question supplied.