ATI Dosage Calculation Proctored Assessment 3.2: Formulas, Specialties & How to Prepare

The ATI Dosage Calculation and Safety 3.2 assessments look different by specialty, but they share the same handful of calculations — the specialty changes the drugs, the patient and the units; it does not change the math. This guide walks through every version, the formulas behind them, and 25 worked practice questions.

For level requirements, passing scores and retake policies that apply across ATI's proctored exams, see the ATI proctored exam guide.

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What is the ATI dosage calculation proctored assessment 3.2?

ATI's Dosage Calculation and Safety series is proctored and split by specialty, with separate RN and PN versions. The specialties in the series are:

• Fundamentals
• Mental Health
• Pediatric Nursing
• Maternal Newborn
• Adult Medical-Surgical and Critical Care (heparin, insulin, titrated drips)

Nursing programs often set a benchmark of 90% or higher — sometimes 100% — with a limited number of attempts.

How the specialty assessments compare

●●● constant · ●● often · ● occasional · — none

RN vs PN: both use the same methods. RN versions lean further into IV push, continuous infusions and reconstitution — see RN Mental Health 3.2. PN versions emphasize oral, IM and subcutaneous doses with simpler IV rates — see PN Mental Health 3.2.

Core skills every 3.2 assessment tests

Dimensional analysis chains these conversion factors together so the unwanted units cancel out, leaving only the unit you need — it's the most reliable way to check that a setup is correct before you calculate.

Fundamentals dosage calculation 3.2 (RN & PN)

The Fundamentals assessment is the broadest of the series and the best place to start — it sets the baseline every other specialty builds on.

What's emphasized:

• Unit conversions
• Tablets
• Oral liquids
• IM/subcut injections
• IV mL/hr, gtt/min, and completion time
• Safe-dose and adult weight-based doses

Mental health dosage calculation 3.2 (RN & PN)

Psychiatric units rely heavily on oral concentrates and IM injections, and PRN maximums matter more here than in almost any other setting.

• Oral concentrates and their calibrated syringes
• STAT and PRN intramuscular doses
• Standard tablet math
• Cumulative PRN maximums across a shift or 24-hour period

Pediatric nursing dosage calculation 3.2 (RN)

Pediatrics is often the hardest test in the series, because every question adds steps: a weight-based dose, then a safe-range check, then a conversion into the volume you'll actually give.

• mg/kg dosing from a weight in kg or lb
• Safe dosage range verification
• Body surface area (BSA) calculations
• Pediatric IV and maintenance fluid rates

There are two RN Pediatrics 3.2 practice tests on this page: the main test above, which includes a free preview and this guide, and a separate 35-question Q&A set from the Carrington College collection for a second full round of practice.

Maternal newborn dosage calculation 3.2 (RN)

This assessment splits into two very different number ranges: the maternal side runs on infusions measured in mU/min and g/hr, while the newborn side runs on tiny weight-based doses measured in kilograms and fractions of a mL.

• Oxytocin titration in milliunits per minute
• Magnesium sulfate infusions in grams per hour
• Newborn weight-based doses and very small IM volumes

Rounding rules that cost students points

• Round once, at the very end of the calculation — not at each intermediate step.
• Use a leading zero and no trailing zero: write 0.5 mL and 5 mL, not .5 mL or 5.0 mL.

The 10 most common dosage calculation mistakes

1. Multiplying pounds by 2.2 instead of dividing.
2. Confusing a mg/kg/dose order with a mg/kg/day order.
3. Missing an mcg↔mg or unit↔milliunit conversion.
4. Mixing up hours and minutes when calculating gtt/min.
5. Reading an oral concentrate's strength as if it were a dilute solution.
6. Rounding too early, before the final step.
7. Forgetting to add prior PRN doses when checking a cumulative maximum.
8. Answering in mg when the question asked for mL (or vice versa).
9. Splitting an unscored tablet or an extended-release (ER) tablet.
10. Skipping the sanity check on the final answer.

How to prepare: a 2-week study plan

If you're preparing for several specialties at once, work through Fundamentals once, then rotate the remaining days between whichever specialty assessments your program requires.

Quick IV rate checker

Use this to check a hand-worked answer — not to replace doing the math yourself.

Practice tests by specialty

Browse all nursing school practice exams →

Glossary of dosage calculation terms

Dimensional analysis

A unit-conversion method that chains conversion factors so unwanted units cancel, leaving the answer in the unit you need.

Desired over Have (D/H × Q)

The formula method: (Desired dose ÷ Have on hand) × Quantity the "Have" comes in = amount to give.

Drop factor

The number of drops per mL delivered by an IV tubing set — 10, 15 or 20 gtt/mL for macrodrip tubing, 60 gtt/mL for microdrip tubing.

Safe dosage range (SDR)

The minimum and maximum dose considered safe for a patient, usually expressed per kg per dose or per day; an order outside this range should be clarified before giving.

BSA (Mosteller)

Body surface area, calculated as √[(height in cm × weight in kg) ÷ 3,600], used to scale certain doses to an individual patient.

Oral concentrate

A high-strength oral liquid (for example 20 mg/mL) that must not be confused with a lower-strength oral solution (for example 20 mg/5 mL) of the same drug.

Reconstitution

Adding a diluent to a powdered medication to create a liquid of a known concentration before it is given.

Milliunit (mU)

One-thousandth of a unit; oxytocin orders are written in milliunits per minute and must be converted to mL/hr for the pump.

PRN maximum

The total dose of a PRN medication that may be given in a defined period (for example, 24 hours); every prior dose in that window counts toward the limit.

Frequently asked questions

More dosage calculation practice tests

For students who have finished the 3.2 series or who are studying a course-specific medication math class, here are related practice tests.

ATI medical dosage exams

HESI dosage calculation (WGU)

Looking for more? All nursing school practice exams · ATI proctored exam guide · Nursing exam bundles

For educational use only. Examples on this page use standard textbook values — always verify doses against current references, your facility's policy and the prescriber's order. Provic Tutors is not affiliated with ATI; ATI® is a trademark of its respective owner, and the practice questions on this page are original. Last reviewed: October 1, 2026.