NCLEX-style dosage calculations: practice problems and exam questions

Medication math practice of the kind that appears on nursing licensing exams such as the NCLEX: tablets and liquids, weight-based and pediatric doses, IV flow and drip rates, infusions and fluid balance.

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Cram pack (PDF)Formula sheets, method steps and practice problems with full solutions, ready to print.

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Topics in this course

  1. Dosage calculationstablets and liquids · weight-based doses · doses and concentrationscalculations
  2. IV infusion ratespump rate · drip rate · time and dose ratecalculations
  3. Pediatric & critical-care dosingpediatric weight-based doses (mg/kg/day divided) · heparin and insulin infusions (units/h, mL/h) · titrated drips (mcg/kg/min to mL/h)calculations
  4. IV fluids & fluid balancemaintenance fluids (Holliday–Segar 4-2-1) · intake and output balance · infusion completion timecalculations
  5. Nursing math & unit conversionsmetric, weight and household units · temperature, 24-hour clock and rounding · dimensional analysis chainscalculations

Exam tips for NCLEX-style dosage calculations

  • Write the units in every step; they tell you whether you multiply or divide.
  • Convert mcg, mg and g before you calculate.
  • Round only at the end, and only as far as the question asks.

Worked examples

Dosage calculationsEasy
? × 100 mg

A patient is prescribed 100 mg of a drug. The tablets on the ward contain 100 mg each. How many tablets n do you give?

100 mg100 mg/tablet

Find n (tablets)

Show hints
  1. Divide the prescribed dose by the strength of one tablet.
  2. Both values are already in mg.
  3. 100/100.
Show the answer and the step-by-step solution

Dose calculation: the amount to give equals what is prescribed divided by what you have, times the quantity it comes in: amount = (desired dose/stock strength) × stock volume. Always keep the units the same (convert g to mg, mg to mcg first) and check that the answer is sensible.

Number of tablets

n = 100/100 = 1 tablet

Answer

n = 1 tablet
IV infusion ratesMedium
1000 mL15 gtt/mL6 h? gtt/min

Infuse 1000 mL over 6 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL6 h15 gtt/mL

Find R (gtt/min)

Show hints
  1. gtt/min = volume × drop factor/time in minutes.
  2. Convert the hours to minutes first.
  3. 6 h = 360 min.
Show the answer and the step-by-step solution

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Time in minutes

6·60 = 360 min

Drip rate

R = 1000·15/360 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

How practising works

  • “Practise this course” mixes problems from all its topics, like a real exam.
  • Every problem has new values, so you learn the method instead of an answer.
  • Stuck? Open a small hint first, and the full explanation only when you need it.
  • Mock exams are timed and have no hints, and you get your score and a full review at the end.

Calculators for this course

Dosage calculator (desired over have)IV flow rate and drip rate calculatorWeight-based dose calculator (mg/kg)mcg/kg/min to mL/h calculator (weight-based infusion)Pediatric safe dose range calculator (mg/kg/day)IV infusion time calculator (when will the infusion finish?)Nursing unit converter (mg, mcg, kg, lb, mL, tsp, °F, °C)Intake and output calculator (fluid balance)Parkland formula calculator (burn fluid resuscitation)Heparin infusion rate calculatorMaintenance fluids calculator (Holliday–Segar)

Related courses

Nursing MathNCLEX-style practice questions (RN)NCLEX-PN-style practice questions (LPN/LVN)Pediatric and Critical-Care DosingPharmacy technician math practiceMaternity NursingPediatric NursingIV Fluids and Fluid Balance
Practise this course for freePractise this courseTake a mock exam5 free problems every day. No card needed.