How many math questions are on the PTCE?
There's no fixed count. Calculations appear mainly inside the Order Entry & Processing domain (22.5% of the 2026 exam), and most candidates report roughly a handful to a dozen math-flavored questions.
Pharmacy Math
Pharmacy Math for the PTCE: Every Formula + the 5 Question Types
By the RxReflex Content Team
Every PTCE math question is one of five types: convert (units), scale (ratio-proportion), concentrate (percent strength), weight-dose (mg/kg), or rate (IV flow). Master the conversion table and one formula per type and you've covered the math — and note: alligation was removed from the 2026 PTCE.
What conversions must I memorize for the PTCE?
| Measure | Equals | Memory anchor |
|---|---|---|
| 1 teaspoon (tsp) | 5 mL | the kitchen-spoon baseline |
| 1 tablespoon (tbsp) | 15 mL | 3 teaspoons |
| 1 fluid ounce (fl oz) | 30 mL | 2 tablespoons |
| 1 cup | 240 mL | 8 fl oz |
| 1 pint | 473 mL (often rounded to 480) | 2 cups |
| 1 gallon | 3,785 mL (≈3,840 by the household chain) | 128 fl oz |
| 1 kilogram (kg) | 2.2 lb | divide pounds by 2.2 → kg |
| 1 grain (gr) | 65 mg | aspirin 5 gr = 325 mg |
| 1 ounce (oz, weight) | 28.35 g (≈30 g by convention) | — |
| 1 inch | 2.54 cm | — |
| 1 g / 1 mg / 1 mcg | 1 g = 1,000 mg = 1,000,000 mcg | each metric step ×1,000 |
lightbulb
Exam tip
Most wrong answers on conversion questions come from the pounds→kilograms step. When a dose is “per kg” and the patient is given in pounds, divide by 2.2 first — before anything else.
What are the 5 PTCE math question types?
| Type | What it asks | The formula |
|---|---|---|
| 1 · Convert | Change units (household ↔ metric) | Use the conversion table above |
| 2 · Scale | “If 250 mg per 5 mL, how many mL for 400 mg?” | Ratio-proportion: cross-multiply, solve for x |
| 3 · Concentrate | Percent strength & dilutions | % w/v = grams per 100 mL (1:1,000 = 1 g per 1,000 mL) |
| 4 · Weight-dose | Pediatric / weight-based dosing | lb ÷ 2.2 = kg, then kg × (mg/kg dose) |
| 5 · Rate | IV flow & drip rates | mL/hr = total mL ÷ hours · gtt/min = (mL/hr × drop factor) ÷ 60 |
Add the everyday retail formula — days supply = quantity dispensed ÷ quantity used per day — and you can classify any math question on the exam in a few seconds. Naming the type first stops the panic; the setup follows automatically.
Worked examples (one per type)
| Problem | Setup | Answer |
|---|---|---|
| 30 tablets, 1 tab twice daily. Days supply? | 30 ÷ 2 per day | 15 days |
| Amoxicillin 250 mg/5 mL. Dose is 400 mg. How many mL? | 250/5 = 400/x → 250x = 2,000 | 8 mL |
| 2.5 g of drug in 50 mL. Percent strength? | 2.5 g ÷ 50 mL × 100 | 5% w/v |
| Child weighs 44 lb. Dose is 10 mg/kg/day. | 44 ÷ 2.2 = 20 kg → 20 × 10 | 200 mg/day |
| 1,000 mL IV over 8 hours. Flow rate? | 1,000 ÷ 8 | 125 mL/hr |
Notice that none of these need advanced math — every one is arithmetic after the right setup. The exam gives you an on-screen calculator; the skill being tested is the setup, not the arithmetic.
Is alligation on the 2026 PTCE?
No. Alligation (the “tic-tac-toe” method for mixing two strengths) and compounding-specific calculations were removed when the content outline changed on January 6, 2026. If a practice bank still drills alligation, it's built on the old outline — full details in what changed on the 2026 PTCE.
How do I get faster at pharmacy math?
- arrow_rightClassify before you calculate. Say the type in your head (“this is a rate problem”) — the formula follows.
- arrow_rightWrite the units into the setup. If the units cancel to what the question asks for, the setup is right.
- arrow_rightSanity-check the size of the answer. A 20 kg child should not get a 2,000 mg dose of most drugs; a 10× error usually means a misplaced decimal.
- arrow_rightDrill a few problems daily. Math speed is a reflex — get the app free and run a 5-minute math round with worked solutions after each answer.
PTCE pharmacy math — FAQ
Can I use a calculator on the PTCE?
Yes — an on-screen calculator is provided at the testing center. The challenge is setting up the problem, not the arithmetic.
Is alligation on the 2026 PTCB exam?
No. Alligation and compounding-specific calculations were removed from the 2026 content outline, effective January 6, 2026.
What's the most important conversion to know?
1 kg = 2.2 lb is the one that decides the most questions, because weight-based (mg/kg) dosing problems start with converting the patient's weight. After that: 1 tsp = 5 mL and 1 fl oz = 30 mL.
What is the days supply formula?
Days supply = total quantity dispensed ÷ quantity used per day. Example: 60 tablets at 1 tablet twice daily = 60 ÷ 2 = 30 days.
Practice every calc type the 2026 PTCE tests
RxReflex drills conversions, days supply, IV rates, percent strength, and mg/kg dosing — every problem with a worked, step-by-step solution. Free to start.
Keep studying
What Changed on the 2026 PTCB ExamNew domain weights, what was removed, and how to adjust your study plan.
Sig Codes Cheat SheetEvery abbreviation you'll see on a prescription — plus the ten you must never write.
How to Read a PrescriptionThe anatomy of an Rx, all ten DAW codes, and how to read an NDC off a stock bottle.Prefer a printable version? Grab “The PTCB Pass Code” free PDF — the highest-yield facts, formulas & traps on 22 pages.
Written and reviewed by the RxReflex Content Team. Educational use only — not medical advice. Exam policies and fees are set by PTCB — always confirm details at ptcb.org. Verify clinical specifics with your pharmacist or a current label source such as DailyMed. RxReflex is not affiliated with or endorsed by the Pharmacy Technician Certification Board (PTCB).