Does the PEBC exam include pharmacy calculations?

Yes. Calculation questions are mixed in throughout the multiple-choice exam rather than grouped into one section. They usually cover dosing (including weight-based and pediatric dosing), concentrations and dilutions, alligation, IV flow rates, compounding, and pharmacokinetic values like creatinine clearance and ideal body weight.

What types of calculations are tested on the PEBC?

The most common types are weight-based and pediatric dosing, percentage strength and dilution problems (% w/v, ppm, alligation), IV infusion and drip rates, compounding math (specific gravity, aliquots), and pharmacokinetic calculations like creatinine clearance and body weight. The practice set above samples across these.

How many calculation questions are on the PEBC exam?

There is no fixed number. The exam is randomized, so the amount of calculation questions changes from one sitting to the next. You might get only a few, or you might get a lot, and there is no guaranteed minimum. What stays consistent is that calculations usually make up a meaningful chunk of the exam, so they are always worth drilling.

How should I study for PEBC calculations?

Drill one calculation type at a time until the setup is automatic, and always write your units out and cancel them to catch mistakes. Review the full reasoning for every question, not just the final number. The explanations on this page are built for that: they show where each wrong answer comes from, which is usually one predictable slip like the wrong base weight or a missed unit conversion.

PEBC Calculations Practice Questions

Calculations come up all over the PEBC exam: dosing, concentrations and dilutions, IV flow rates, compounding, and pharmacokinetics. They are also some of the most learnable marks on the test, because once you know the method it works the same way every time.

Work through the questions below. Each one shows you why the right answer is right and why every wrong answer is wrong, so you can find the exact step you missed instead of just checking a final number.

Written and reviewed against current Canadian guidelines and references.

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How to approach a PEBC calculation

1Start by writing down exactly what the question asks for, including the units of the final answer. Half of all calculation errors are answering the wrong question.
2Carry your units through every line and cancel them as you go. If the units left at the end are not the units the answer needs, your setup is wrong, even if the arithmetic is clean.
3Convert percentages and ratio strengths into mg/mL before you do anything else. Most concentration and dilution mistakes happen because the strength was never translated first.
4Know the classic traps: using total body weight when the question wants ideal body weight, forgetting to split a daily dose into individual doses, and swapping the two stock concentrations in an alligation.
5Estimate the rough size of the answer before you calculate. If your final number is ten times bigger or smaller than your estimate, you caught a decimal error before it cost you a mark.

Practice questions

Tap an answer to see why each option is right or wrong.

Question 1Pharmacy Calculations

Estimate the osmolarity of D5W using dextrose molecular weight 180 and no dissociation.

Incorrect · Answer: A

PEBC Yield: Highcalculationdispensingerror-prevention

A) (Correct)

Correct - D5W contains 50 g/L. 50/180 = 0.278 mol/L, or about 278 mOsm/L because dextrose does not dissociate.

252 mOsm/L is low; it uses a larger effective molecular weight.

300 mOsm/L is a rough physiologic estimate but not the calculation from 50 g/L and MW 180.

556 mOsm/L doubles the answer as if dextrose dissociated into 2 particles.

Question 2Pharmacy Calculations

An 18 kg child is prescribed amoxicillin 45 mg/kg/day divided TID. The suspension is 250 mg/5 mL. What volume is needed per dose?

Incorrect · Answer: A

PEBC Yield: Highcalculationdose-adjustmentdispensing

A) (Correct)

Correct - the daily dose is 45 x 18 = 810 mg/day. Dividing TID gives 270 mg per dose, and 270 mg at 50 mg/mL is 5.4 mL.

4.5 mL is low; it corresponds to 225 mg per dose rather than the required 270 mg.

6.0 mL is high; it would provide 300 mg per dose.

16.2 mL is the total daily volume, not the per-dose volume after dividing TID.

Question 3Pharmacy Calculations

Which expression is NOT equivalent to a 1:500 w/v solution?

Question 4Pharmacy Calculations

A TPN provides 150 g dextrose, 70 g amino acids, and 50 g lipid. Using 3.4, 4, and 10 kcal/g, what total kcal is provided?

Incorrect · Answer: C

PEBC Yield: Highcalculationdispensingerror-prevention

1190 kcal is low; it undercounts one of the macronutrient calorie contributions.

1240 kcal is low; it misses 50 kcal from the total.

C) (Correct)

Correct - dextrose gives 150 x 3.4 = 510 kcal, amino acids give 70 x 4 = 280 kcal, and lipid gives 50 x 10 = 500 kcal. Total = 1290 kcal.

1390 kcal is high; it overcounts the total by 100 kcal.

Question 5Dose Calculations

A physician orders vancomycin 1 g in 250 mL normal saline to infuse over 2 hours. The IV set delivers 15 drops/mL. What is the required drip rate in drops per minute?

Incorrect · Answer: B

PEBC Yield: Highcalculation

This results from using 1.5 hours (90 minutes) instead of 2 hours. With the correct 120-minute duration, the drip rate is 31 drops/min.

B) (Correct)

Correct. Drip rate = (volume x drop factor) / time in minutes = (250 mL x 15 drops/mL) / 120 min = 3750 / 120 = 31.25, rounded to 31 drops/min.

This results from using 100 minutes (1 hr 40 min) instead of 120 minutes as the infusion time. The correct time is 2 hours = 120 minutes.

This results from using a drop factor of 12 drops/mL instead of 15 drops/mL. With 15 drops/mL, the rate is 250 x 15 / 120 = 31.25 drops/min.

Question 6Pharmacy Calculations

Eye drops are prescribed 1 drop OU TID for 28 days. If 1 mL contains 20 drops and each bottle is 5 mL, how many bottles are needed?

Incorrect · Answer: C

PEBC Yield: Highcalculationdispensingerror-prevention

1 bottle has 100 drops, which is not enough for 168 drops.

3 bottles would cover the course, but it is more than the minimum quantity needed.

C) (Correct)

Correct - OU TID is 6 drops/day. Over 28 days, 168 drops are needed. Each 5 mL bottle has 100 drops, so 2 bottles are needed.

4 bottles is more than the calculated minimum quantity.

Question 7Pharmacy Calculations

How much 30% ointment and plain base are needed to prepare 120 g of 10% ointment?

Question 8Compounding Math

A pharmacist is preparing a compounded ointment. The formula calls for 120 g of an ingredient with a specific gravity of 0.85. What volume of this liquid ingredient should be measured?

Incorrect · Answer: A

PEBC Yield: Highcalculation

A) (Correct)

Correct. Volume = weight / specific gravity = 120 g / 0.85 = 141.2 mL, rounded to 141 mL. Since SG < 1, the substance is lighter than water, so more volume is needed.

This assumes 1 g = 1 mL, ignoring specific gravity entirely. Since the specific gravity is 0.85, the liquid is lighter than water and requires a greater volume to achieve 120 g.

This results from multiplying the weight by the specific gravity (120 x 0.85 = 102) instead of dividing. When specific gravity is less than 1, the volume is larger than the weight in grams.

This results from using an incorrect specific gravity value or rounding error in the division. The correct calculation is 120 / 0.85 = 141 mL.

Question 9Compounding Math

A pharmacist needs to prepare 200 mL of a 3% w/v hydrocortisone cream using a 5% w/v stock cream and a 1% w/v diluting cream. Using the alligation method, what volume of the 5% stock cream is required?

Incorrect · Answer: A

PEBC Yield: Highcalculation

A) (Correct)

Correct. Alligation: stock (5%) minus target (3%) = 2 parts diluent. Target (3%) minus diluent (1%) = 2 parts stock. Ratio is 2:2, so equal volumes. 200 mL total divided equally = 100 mL of the 5% stock cream.

This results from reversing the alligation parts, assigning the diluent proportion to the stock cream. The stock and diluent each contribute 2 parts, yielding equal volumes of 100 mL, not 125 mL.

This would result from an error in the alligation calculation, assigning the wrong proportional parts to the stock cream. Using alligation: 5% stock minus 3% target = 2 parts diluent; 3% target minus 1% diluent = 2 parts stock. Equal parts means 100 mL of each, not 75 mL.

This results from calculating the diluent volume as only 50 mL and assigning the remainder to stock. The correct alligation yields equal parts (2:2), so each component is 100 mL.

Question 10Compounding Math

A pharmacist must prepare 250 mL of a 15% v/v ethanol solution. The pharmacy stocks 95% v/v ethanol and purified water. What volume of the 95% ethanol is needed?

Incorrect · Answer: B

PEBC Yield: Highcalculation

This results from using a target concentration of 17% or a stock concentration of 84% in the dilution equation. The correct answer is 39.5 mL.

B) (Correct)

Correct. V1 = C2 x V2 / C1 = 15% x 250 mL / 95% = 3750 / 95 = 39.5 mL of the 95% ethanol, with purified water added to final volume of 250 mL.

This results from using 70% instead of 95% as the stock concentration, or from a multiplication error. C1V1 = C2V2 gives V1 = (15 x 250) / 95 = 39.5 mL.

This results from rounding errors or using an incorrect target volume in the dilution equation. The correct calculation yields 39.5 mL.

Want the full bank?

These are a sample. The full bank adds full-length cases and timed mock exams.

Sample full case

One patient with several linked questions, the format the real exam uses for case clusters.

You are a pharmacist at a hospital compounding pharmacy. A physician orders a 2% lidocaine solution for a series of nerve block procedures. Your pharmacy stocks a 10% lidocaine solution (50 mL vials) and sterile normal saline (0.9% NaCl) as the diluent. The order is for 200 mL of 2% lidocaine. The pharmacy also has a supply of 4% lidocaine solution available on the shelf, and the procedure room has requested that 15 mL be set aside as a flush — this volume is separate from the 200 mL order and is not part of this calculation.

Question 1Dose Calculations

How many millilitres of the 10% lidocaine stock solution are required to prepare exactly 200 mL of 2% lidocaine solution?

Incorrect · Answer: D

PEBC Yield: Highdilutionstock-solutionconcentrationcompounding

20 mL results from dividing the target concentration by the stock concentration (2/10 = 0.2) and then multiplying by only the stock volume relationship incorrectly — or from halving the correct answer (40 mL ÷ 2). This error treats the concentration ratio as the volume ratio without accounting for the total final volume of 200 mL.

10 mL results from applying a 1:10 dilution (10% → 1%) by mistake, or from computing C₂/C₁ × some volume without correctly using the total final volume. This would produce approximately 0.5% lidocaine — well below the target.

100 mL results from confusing the dilution factor with the volume: since the stock is 5× more concentrated, some students divide total volume by 5 and then multiply incorrectly — or they attempt to use the 4% stock concentration in the calculation by mistake. Using 100 mL of 10% in 200 mL total would produce a 5% solution, not 2%.

D) (Correct)

Correct. Apply the dilution equation C₁V₁ = C₂V₂: (10%)(V₁) = (2%)(200 mL). Solving: V₁ = (2 × 200) / 10 = 400 / 10 = 40 mL. Therefore, take 40 mL of 10% lidocaine and add sterile saline to a final volume of 200 mL (i.e., add 160 mL of saline). The 15 mL flush request and the 4% stock on the shelf are irrelevant noise. Key point: Compounding math is safest when the concentration meaning is translated first, then the equation is solved with units carried through to the final answer.

Question 2Dose Calculations

A compounding order requires 500 mL of a 35% dextrose solution. The pharmacy stocks 70% dextrose (in 500 mL bags) and 5% dextrose (in 1,000 mL bags). Using the alligation method, how many millilitres of 70% dextrose and how many millilitres of 5% dextrose are needed?

Incorrect · Answer: A

PEBC Yield: Highalligationconcentration-mixingcompoundingcross-subtraction

A) (Correct)

Correct. Set up the alligation grid with 70% on top-left, 5% on bottom-left, and target 35% in the centre. Diagonal subtraction: parts of 70% = |35 − 5| = 30 parts; parts of 5% = |70 − 35| = 35 parts. Total parts = 30 + 35 = 65 parts. Volume of 70% = (30/65) × 500 mL = 230.77 mL ≈ 230 mL. Volume of 5% = (35/65) × 500 mL = 269.23 mL ≈ 269 mL. Verification: (230 × 0.70) + (270 × 0.05) = 161 + 13.5 = 174.5 g dextrose; 174.5 ÷ 500 = 34.9% ≈ 35%. ✓ Key point: Compounding math is safest when the concentration meaning is translated first, then the equation is solved with units carried through to the final answer.

250 mL of each results from assuming that a target concentration exactly halfway between two stocks requires equal volumes. This is only true when the two stock concentrations are equidistant from the target — here, 70% is 35 units above 35%, and 5% is 30 units below 35%. The distances are unequal, so the volumes are unequal. This is the most common alligation error.

This reverses the alligation assignment. The parts for each stock come from the distance between the target and the opposite stock, not the same-side stock. Correct alligation gives 30 parts of 70% and 35 parts of 5%, so the batch needs about 231 mL of 70% and 269 mL of 5%. Reversing those volumes would make the final preparation too concentrated.

333 mL of 70% and 167 mL of 5% results from inverting the alligation diagonal assignments — placing 35 parts with the 70% stock and 30 parts with the 5% stock, which is backwards. The parts for each stock equal the absolute difference between the TARGET and the OPPOSITE stock (not the same stock).

Question 3Dose Calculations

A topical solution contains 0.025% w/v triamcinolone acetonide. Which expression is equivalent?

Incorrect · Answer: D

PEBC Yield: Highconcentration-conversionpercent-w-vmg-per-mlratio-strength

2.5 mg/mL results from multiplying instead of dividing during the % → mg/mL conversion (0.025 × 100 = 2.5 instead of 0.025 ÷ 100 × 1,000 = 0.25). This is a unit-manipulation error where the student accidentally moves the decimal in the wrong direction. The paired ratio strength of 1 in 400 is internally consistent with 2.5 mg/mL but wrong.

0.025 mg/mL reflects failing to convert % w/v correctly — the student reads 0.025% and writes 0.025 mg/mL without applying the ÷ 100 mL and × 1,000 mg/g conversion chain. The ratio strength of 1 in 40,000 would correspond to a 0.0025% w/v solution, not 0.025%. Both parts of this option are one decimal place off.

0.25 mg/mL is correct for part (i) — this part matches the correct answer. However, 1 in 40,000 is wrong for part (ii); it corresponds to a concentration of 0.025 mg/mL, not 0.25 mg/mL. This distractor catches students who calculate the mg/mL correctly but then slip a decimal when computing the ratio strength.

D) (Correct)

Correct. Step 1 — Convert % w/v to mg/mL: % w/v means grams of solute per 100 mL. So 0.025% w/v = 0.025 g per 100 mL = 0.00025 g/mL = 0.25 mg/mL. Step 2 — Convert to ratio strength: ratio strength is expressed as 1 part drug in X parts total. If concentration = 0.25 mg/mL = 0.00025 g/mL, then 1 g is dissolved in (1 ÷ 0.00025) mL = 4,000 mL. Ratio strength = 1 in 4,000. Verification: 1 g / 4,000 mL × 1,000 mg/g = 0.25 mg/mL. ✓ Key point: Compounding math is safest when the concentration meaning is translated first, then the equation is solved with units carried through to the final answer.

Question 4Dose Calculations

The compounding pharmacist prepares a water-containing oral suspension of metronidazole 50 mg/mL. The preparation is stored in the refrigerator (2–8°C). The pharmacist prepares a batch of 300 mL but anticipates that 60 mL will be wasted during the compounding process. The preparation is completed on April 9, 2026. According to NAPRA guidance for non-sterile water-containing oral formulations stored at controlled cold temperatures, what is the latest acceptable beyond-use date, and how many millilitres of usable product are available to dispense?

Incorrect · Answer: B

PEBC Yield: Highbeyond-use-datingbudnon-sterile-compoundingwater-containing-formulationnapra

October 9, 2026 (6 months) applies to non-aqueous formulations, not water-containing oral formulations. The 6-month BUD rule applies when there is no water in the formulation — water dramatically reduces stability by enabling hydrolysis and microbial growth. Applying the non-aqueous rule here is a category error. The waste calculation (240 mL) is correct.

B) (Correct)

Correct. Part 1 — BUD: Per NAPRA guidance, water-containing oral formulations stored at controlled cold temperatures (2–8°C) have a maximum BUD of 14 days. Preparation date = April 9, 2026; BUD = April 9 + 14 days = April 23, 2026. Part 2 — Dispensable volume: 300 mL prepared − 60 mL anticipated waste = 240 mL available to dispense. The waste volume is subtracted before dispensing — you cannot dispense product that is lost in the compounding process. Key point: Compounding math is safest when the concentration meaning is translated first, then the equation is solved with units carried through to the final answer.

30 days (May 9, 2026) applies to water-containing dermal/topical, mucosal liquid, and semi-solid formulations — NOT oral formulations. Water-containing oral formulations stored cold are limited to 14 days by NAPRA guidance. This is the most common BUD category confusion on PEBC calculation questions.

April 23, 2026 is the correct BUD — this part is right. However, 300 mL ignores the 60 mL wastage. Dispensing 300 mL would require producing more than the available yield. Always subtract anticipated compounding waste from the total batch size to determine dispensable quantity.

Full-length cases like this, across every PEBC domain, live in the question bank.

Frequently asked questions

Does the PEBC exam include pharmacy calculations?: Yes. Calculation questions are mixed in throughout the multiple-choice exam rather than grouped into one section. They usually cover dosing (including weight-based and pediatric dosing), concentrations and dilutions, alligation, IV flow rates, compounding, and pharmacokinetic values like creatinine clearance and ideal body weight.
What types of calculations are tested on the PEBC?: The most common types are weight-based and pediatric dosing, percentage strength and dilution problems (% w/v, ppm, alligation), IV infusion and drip rates, compounding math (specific gravity, aliquots), and pharmacokinetic calculations like creatinine clearance and body weight. The practice set above samples across these.
How many calculation questions are on the PEBC exam?: There is no fixed number. The exam is randomized, so the amount of calculation questions changes from one sitting to the next. You might get only a few, or you might get a lot, and there is no guaranteed minimum. What stays consistent is that calculations usually make up a meaningful chunk of the exam, so they are always worth drilling.
How should I study for PEBC calculations?: Drill one calculation type at a time until the setup is automatic, and always write your units out and cancel them to catch mistakes. Review the full reasoning for every question, not just the final number. The explanations on this page are built for that: they show where each wrong answer comes from, which is usually one predictable slip like the wrong base weight or a missed unit conversion.