The single most consequential rule in the Common Registration Assessment is one sentence long: you must achieve the pass mark in both Part 1 and Part 2 in the same sitting, and compensation between the parts is not permitted. A superb performance in clinical therapeutics will not save you from a failed calculations paper. That rule, more than any other feature of the exam, should determine how you prepare, because it means you are not preparing for one assessment with two halves. You are preparing for two independent hurdles, and you must clear both on the same day.
Key takeaways
- Part 1 is 40 calculation questions in 120 minutes, answered by typing a number rather than choosing an option.
- Part 2 is 120 selected-response questions in 150 minutes, comprising single best answers and extended matching sets.
- Both must be passed in the same sitting, and there is no compensation between them.
- From 2026 a calculator is permitted in both parts, so advice to drill mental arithmetic for Part 2 is out of date.
- Track two separate accuracy figures, because a combined percentage conceals which hurdle you are about to fail.
Two papers, two entirely different skills
Look at what each paper actually asks and the case for separate systems makes itself.
Part 1 gives you 40 pharmacy and healthcare calculations in two hours. You are not selecting from options: you type a numerical answer into a box, with the required units stated. That is three minutes per question, which sounds generous until you notice what the format removes.
Part 2 gives you 120 selected-response questions in two and a half hours, made up of single best answer items and extended matching sets in which two questions share a common list of eight options. That works out at about seventy-five seconds per question, and it tests clinical therapeutics, law, governance and regulation, and professional practice within the framework's domains of person-centred care and collaboration.
Arithmetic under time pressure and applied clinical judgement are simply not the same competency. Candidates who are strong at one and weak at the other are common, and a single blended revision plan tends to reinforce the strength and neglect the weakness.
Why numerical entry changes everything in Part 1
This is the feature of Part 1 that candidates consistently underrate, and it deserves a section of its own.
In a multiple choice paper, the options are a safety net. You can eliminate implausible answers. You can work backwards from the choices. If your calculation produces something that is not on the list, you know immediately that you have made an error, and you get a chance to find it. Even a total guess has a one in five chance.
Part 1 removes all of that. You type a number. If your decimal point is misplaced, there is no option list to tell you so. If you have used micrograms where the question wanted milligrams, nothing catches it. A wrong answer is simply wrong, with no partial credit for a sound method and one slip, and a blank scores nothing.
The consequence for your revision is direct: your calculation practice must include your own checking, because the exam will not check for you. Estimate the expected magnitude before you calculate. Confirm the units the question wants against the units you have produced. Sanity-check the result against clinical plausibility, because a paediatric dose of several grams should stop you cold even if the arithmetic looks tidy.
The 2026 calculator change
One specific update matters, because a lot of published advice predates it. From the 2026 sittings, a calculator is permitted in both Part 1 and Part 2, either the onscreen calculator built into the assessment platform or a physical model from the approved list.
Older guidance telling you to drill mental arithmetic in preparation for a calculator-free Part 2 is therefore obsolete. That does not make calculation skill less important, and it certainly does not remove the need to practise, because the calculator solves the arithmetic and not the method. Choosing the right formula, converting units correctly, and knowing what the answer should look like are all still yours to get right, and they are where the marks are actually lost.
Practise with the calculator you will actually use, since fumbling an unfamiliar interface under time pressure is an entirely avoidable way to lose minutes.
Set independent targets, and track them separately
Because there is no compensation, an overall percentage is not merely unhelpful, it is actively misleading. It can rise steadily while your calculations performance sits below the line.
Keep two dashboards. For Part 1, track accuracy by calculation type: doses and dose regimens, weight-based and paediatric dosing, unit conversions, infusion rates, concentrations and dilutions, displacement values, and renal dose adjustment. Weakness here is almost always specific rather than general, and it is fixable once you can name it.
For Part 2, track by content area: clinical therapeutics, law and governance, and professional practice. It is entirely common to be strong in therapeutics and thin in law, and the exam maps its questions to learning outcomes weighted high, medium and low, so knowing where the weight sits should inform where your hours go.
Set a separate readiness threshold for each paper, and do not sit the assessment until you clear both.
Understand how the standard is set
One useful piece of context. The passing standard is set using a modified Angoff methodology with the addition of one standard error of measurement, and maintained through item response theory, which means the pass mark varies between sittings to reflect the difficulty of the paper while the underlying standard stays constant.
The practical implication is to stop chasing a specific percentage you heard about from a previous cohort. The number moves. What does not move is the standard of competence being demanded, so build to a comfortable margin above your best guess at the threshold, rather than aiming to scrape a figure that may not apply to your sitting.
Where iatroX fits
iatroX's GPhC bank covers both parts of the assessment, with calculation practice as its own tracked domain rather than being folded into a single blended score, which is exactly the separation the no-compensation rule demands. The adaptive engine targets the specific calculation types and therapeutic areas where you are genuinely weak, spaced repetition holds the law, governance and monitoring detail that decays quickly, and explanations are grounded in current guidance including the SmPC. Missed questions can be opened in the Socratic Tutor, which asks you to reason before it explains. Try it with free sample questions at iatroX. For diagnosing why your calculations go wrong, see the calculation error taxonomy.
Frequently asked questions
Do I have to pass both parts of the GPhC CRA in the same sitting? Yes. You must achieve the pass mark or above in both Part 1 and Part 2 in the same sitting, and compensation between the parts is not permitted. A strong Part 2 will not rescue a failed Part 1.
What is the format of the CRA? Part 1 is 40 calculation questions in 120 minutes, answered by typing a numerical value. Part 2 is 120 selected-response questions in 150 minutes, comprising single best answers and extended matching sets that share eight options across two questions.
Can I use a calculator in the GPhC CRA? Yes, in both parts from the 2026 sittings, using either the onscreen calculator or an approved physical model. Older advice about drilling mental arithmetic for Part 2 is out of date, though method and unit conversion still matter enormously.
Why is Part 1 harder than its question count suggests? Because you type a number rather than choosing from options. There is no option list to eliminate against, no working backwards, and no signal that your decimal point is misplaced. You must build your own checking into every calculation.