Drug Calculations Practice Questions for Student Nurses
Build your confidence with 40 free nursing drug calculation practice questions, progressing from essential maths and unit conversions through tablets, liquid medicines and introductory IV calculations.
How to use this resource
Work through the questions in order and try each calculation before checking the worked solution. The questions become progressively more challenging, so start with the essential maths and unit conversions before moving on to tablets, liquid medicines, mixed calculations and introductory IV calculations. Keep a calculator and a notebook nearby, and pay particular attention to units, decimal places and rounding.
Essential Maths & Unit Conversions
Start with the foundations. These questions check the core conversions and numerical skills used throughout nursing drug calculations. Try each question before opening the worked solution.
Convert 2.5 g into milligrams.
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2.5 ร 1000 = 2500
Answer: 2500 mg
Convert 750 mg into grams.
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750 รท 1000 = 0.75
Answer: 0.75 g
Convert 0.4 g into milligrams.
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0.4 ร 1000 = 400
Answer: 400 mg
Convert 3500 micrograms into milligrams.
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3500 รท 1000 = 3.5
Answer: 3.5 mg
Convert 0.6 mg into micrograms.
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0.6 ร 1000 = 600
Answer: 600 micrograms
Convert 1.25 litres into millilitres.
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1.25 ร 1000 = 1250
Answer: 1250 mL
Convert 450 mL into litres.
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450 รท 1000 = 0.45
Answer: 0.45 litres
A patient requires 1.5 g of a medicine. How many milligrams is this?
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1.5 ร 1000 = 1500
Answer: 1500 mg
A medicine contains 250 micrograms. Express this dose in milligrams.
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250 รท 1000 = 0.25
Answer: 0.25 mg
A fluid bag contains 0.75 litres. What volume is this in millilitres?
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0.75 ร 1000 = 750
Answer: 750 mL
Tablet & Capsule Calculations
Now apply your conversion skills to common tablet and capsule calculations. Work out how many tablets or capsules are needed from the prescribed dose and the strength available.
A patient is prescribed 500 mg of a medicine. Tablets available contain 250 mg each. How many tablets are required?
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Strength available = 250 mg per tablet
500 รท 250 = 2
Answer: 2 tablets
A patient is prescribed 1 g of a medicine. Tablets available contain 500 mg each. How many tablets are required?
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1000 รท 500 = 2
Answer: 2 tablets
A patient requires 750 mg of a medicine. Tablets available contain 250 mg each. How many tablets are required?
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Answer: 3 tablets
A patient is prescribed 375 mg. Tablets available contain 250 mg each. How many tablets are required?
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Answer: 1.5 tablets
A patient is prescribed 125 mg. Tablets available contain 250 mg each. How many tablets are required?
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Answer: 0.5 tablet
A patient requires 1.5 g of a medicine. Tablets available contain 500 mg each. How many tablets are required?
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1500 รท 500 = 3
Answer: 3 tablets
A patient is prescribed 600 mg. Capsules available contain 200 mg each. How many capsules are required?
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Answer: 3 capsules
A patient requires 0.75 g of a medicine. Capsules available contain 250 mg each. How many capsules are required?
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750 รท 250 = 3
Answer: 3 capsules
A patient is prescribed 50 micrograms. Tablets available contain 25 micrograms each. How many tablets are required?
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Answer: 2 tablets
A patient is prescribed 1.25 g. Tablets available contain 500 mg each. How many tablets are required?
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1250 รท 500 = 2.5
Answer: 2.5 tablets
Liquid Medication Calculations
These questions focus on liquid medicines. Use the prescribed dose, the strength available and the stock volume to calculate how many millilitres are required.
A patient is prescribed 250 mg. The liquid medicine contains 125 mg in 5 mL. How many millilitres are required?
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Answer: 10 mL
A patient requires 500 mg. The medicine contains 250 mg in 5 mL. What volume should be given?
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Answer: 10 mL
A patient is prescribed 150 mg. A liquid contains 75 mg in 5 mL. How many millilitres are required?
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Answer: 10 mL
A patient requires 300 mg. The stock solution contains 200 mg in 5 mL. What volume is required?
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Answer: 7.5 mL
A patient is prescribed 1 g. The medicine contains 500 mg in 10 mL. How many millilitres are required?
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1000 รท 500 ร 10 = 20 mL
Answer: 20 mL
A patient requires 375 mg. The liquid contains 250 mg in 5 mL. What volume should be administered?
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Answer: 7.5 mL
A patient is prescribed 600 mg. The available liquid contains 300 mg in 5 mL. How many millilitres are needed?
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Answer: 10 mL
A patient requires 125 mg. The stock medicine contains 250 mg in 5 mL. What volume is required?
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Answer: 2.5 mL
A patient is prescribed 0.75 g. The medicine contains 250 mg in 5 mL. How many millilitres should be given?
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750 รท 250 ร 5 = 15 mL
Answer: 15 mL
A patient requires 450 mg. The medicine contains 300 mg in 10 mL. What volume should be administered?
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Answer: 15 mL
Mixed Clinical Calculations
Ready for a greater challenge? These questions mix together the skills you have practised so far. Read each question carefully, check that the units match and decide which calculation you need before opening the worked solution.
A patient is prescribed 1.2 g of a medicine. Tablets available contain 400 mg each. How many tablets are required?
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1200 รท 400 = 3
Answer: 3 tablets
A patient requires 300 micrograms of a medicine. Tablets available contain 0.15 mg each. How many tablets are required?
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300 รท 150 = 2
Answer: 2 tablets
A patient is prescribed 0.6 g of a liquid medicine. The available medicine contains 200 mg in 5 mL. What volume is required?
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600 รท 200 ร 5 = 15 mL
Answer: 15 mL
A patient requires 750 micrograms of a medicine. The liquid available contains 0.5 mg in 2 mL. What volume should be administered?
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750 รท 500 ร 2 = 3 mL
Answer: 3 mL
A patient is prescribed 1.5 g of a medicine. The liquid available contains 250 mg in 5 mL. What volume is required?
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1500 รท 250 ร 5 = 30 mL
Answer: 30 mL
Introductory IV & Infusion Calculations
Finish with five introductory IV and infusion calculations. These questions focus on calculating simple infusion rates and drip rates. Work carefully with time, volume and units before checking the worked solution.
A patient is prescribed 1000 mL of IV fluid to run over 8 hours. What is the infusion rate in mL/hour?
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1000 รท 8 = 125
Answer: 125 mL/hour
A patient requires 500 mL of IV fluid over 4 hours. What infusion rate should be set in mL/hour?
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Answer: 125 mL/hour
A 750 mL infusion is prescribed to run over 6 hours. What is the required rate in mL/hour?
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Answer: 125 mL/hour
A patient is to receive 1000 mL over 10 hours. The giving set delivers 20 drops per mL. Calculate the drip rate in drops per minute.
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Drip rate = Volume ร Drop factor รท Time
1000 ร 20 รท 600 = 33.3
Answer: approximately 33 drops/minute
A patient is prescribed 500 mL of IV fluid over 5 hours. The giving set delivers 20 drops per mL. Calculate the drip rate in drops per minute.
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Drip rate = Volume ร Drop factor รท Time
500 ร 20 รท 300 = 33.3
Answer: approximately 33 drops/minute
Common Drug Calculation Mistakes to Avoid
Getting the arithmetic right is only part of a safe drug calculation. Develop the habit of checking the units, considering whether your answer is reasonable and reviewing your calculation before confirming your final answer.
Not matching the units
Before calculating, check whether the prescribed dose and the available medicine use the same units. Convert grams, milligrams or micrograms where necessary.
Decimal-place errors
A misplaced decimal point can dramatically change a calculated dose. Take particular care when working with values below one and when converting between units.
Using the wrong information
Identify the required dose, the strength available and, for liquid medicines, the volume containing that strength before beginning the calculation.
Not checking the final answer
Ask whether your answer is sensible. An unexpectedly large or small answer is a reason to stop and check the units and calculation again.
Want to build stronger drug calculation confidence?
Practice questions are useful for identifying what you can already do and where you need more support. NurseNet's structured Drug Calculations course focuses on building the underlying maths skills first and then applying them to nursing calculations.
