Lesson overview
Weight-Based Dosage Calculations (mg/kg)
Ready when you are
Start with short teaching slides, then answer the lesson questions. Your progress stays on this browser.
Learning outcomes
What you will learn
- explain what mg/kg means in plain English
- tell the difference between mg/kg/dose and mg/kg/day
- use a weight in kg to calculate a medication dose in mg
- split a daily total into equal doses only when the order tells you to
- convert pounds to kilograms for a supplied practice problem while recognising that clinical medication weights should be verified and documented in kg
- recognise when medicine-specific maximums, obesity or enteral-route considerations require a separate authorised check
- convert a calculated mg dose into mL only when a liquid volume is required
Clinical connection
Why this matters
Weight-based questions become confusing when /dose and /day are treated as the same instruction, or when the weight, medicine dose and liquid volume are mixed into one calculation. Keeping each job separate makes the maths easier to follow and check.
Quick concept
How weight-based dosage calculations work
Start with the verified weight in kilograms and the ordered dose rate. Multiply kg by mg/kg to find the medication amount in mg. Keep mg/kg/dose separate from mg/kg/day: a daily total is divided only when the order states that the daily amount is split into doses. If the question then asks for mL, use the supplied concentration as a second step.
Formula
dose (mg) = weight (kg) × ordered dose rate (mg/kg)
Worked example
Educational example: a practice order is 7.5 mg/kg/dose for a 20 kg patient.
20 kg × 7.5 mg/kg/dose = 150 mg/dose
Answer: 150 mg per dose
Weight-based arithmetic does not establish whether a dose is clinically appropriate. In practice, verify the current order, the correct dosing weight, the medicine-specific reference, stated maximums and any required independent checks.
Lesson plan
How the lesson works
- 1
Learn
Short teaching slides explain one idea at a time with plain-language examples.
- 2
Practise
Answer calculation or scenario questions and receive immediate feedback.
- 3
Finish
Complete the lesson check and save your learning progress on this browser.
Keep going
Learn, practise, apply and check this skill
Use the page that matches what you need next. Each resource has a different job, so the lesson can stay focused on teaching the skill.
Practise
Weight-based dosage practice questions
Practise mg/kg, mg/kg/day, divided-dose and dose-to-volume questions across four levels.
Understand
Weight-based medication dosing guide
Review per-dose versus per-day wording, kg conversion and the two-stage mg/kg-to-mL pathway.
Check
mg/kg to mL Calculator
Check arithmetic when the verified weight, ordered mg/kg rate and supplied concentration are already known.
Apply
Pediatric Care cases
Apply weight-based calculations inside evolving child-health scenarios where the maths has a clinical purpose.