The IISER Aptitude Test (IAT) is the entrance route to the five-year BS-MS dual degree at the Indian Institutes of Science Education and Research. It is a small, sharp paper — far shorter than NEET or JEE Main — and that shortness changes how you should prepare for it.
Because IISER publishes year-specific rules, treat this article as an orientation and confirm every number for your year on the official IISER admissions website.
Who conducts IAT and what it admits you to
IAT is conducted by the IISERs themselves, not by the NTA. It is used for admission to the BS-MS dual degree programme at IISER campuses including Berhampur, Bhopal, Kolkata, Mohali, Pune, Thiruvananthapuram and Tirupati. Some campuses also run other programmes with their own criteria, so read the brochure for the specific institute you are aiming at.
The programme itself matters for how you should think about the exam. BS-MS is a research-oriented degree: you spend five years in a science-first environment, with a research project rather than a placement-first structure. IAT is designed to select students who reason well in science, not students who have memorised the most.
The IAT exam pattern
Recent IAT papers have followed this structure:
| Element | Detail |
|---|---|
| Mode | Computer-based test (CBT) |
| Total questions | 60 multiple-choice questions |
| Subjects | Biology, Chemistry, Mathematics, Physics |
| Questions per subject | 15 |
| Total marks | 240 |
| Marking | +4 correct, −1 incorrect, 0 unattempted |
| Duration | 180 minutes |
| Language | English |
Two structural facts drive strategy:
- All four subjects carry 25% weight. Fifteen questions is 60 marks. Writing off a subject means surrendering a quarter of the paper before you begin.
- Three hours for 60 questions is generous. That is three minutes per question, roughly triple the per-question time of NEET. IAT is not a speed test; it is an accuracy and reasoning test. Aspirants who rush out of habit lose marks they did not need to lose.
Marking scheme: why accuracy beats attempts
With +4 and −1:
- A blind guess among four options has a negative expected value.
- A guess between two options has a clearly positive expected value.
- Ten careless attempts can wipe out the gain from two extra correct answers.
Since the paper is short, each question is worth a larger share of your final score than in a 180-question exam, which means each careless mistake also costs more. Most well-prepared candidates end up attempting somewhere between 45 and 52 questions with high accuracy, rather than all 60.
Syllabus level
The IAT syllabus is based on the NCERT Class 11 and 12 curriculum in Physics, Chemistry, Mathematics and Biology. The level of individual questions varies:
- Biology: largely NCERT-fact and concept based, with genetics, physiology, ecology and cell biology appearing regularly.
- Chemistry: inorganic and organic stay close to NCERT; physical chemistry needs genuine numerical practice.
- Mathematics: Class 11–12 level, with calculus, algebra, coordinate geometry and probability well represented.
- Physics: the section that most resembles JEE Main in difficulty, especially mechanics and electromagnetism, with a reasoning flavour rather than long computation.
For a chapter-level breakdown, read our IAT syllabus guide, and work through it using the free chapter notes and 30-question tests in the IISER IAT Self Study section.
Eligibility, in outline
Eligibility for IAT is based on passing Class 12 (or equivalent) in the science stream in a recent year, with a minimum aggregate that IISER specifies in each year's brochure, and subject requirements that vary by board. Categories such as SC, ST and PwD have relaxed minimum marks as notified.
Because these thresholds, the qualifying years and the accepted board list are revised, do not rely on a forum post or a coaching page — including this one — for eligibility. Read the current official brochure and, if anything is ambiguous, write to the admissions office named in it.
How IAT differs from JEE Main and NEET
| Aspect | IAT | JEE Main | NEET-UG |
|---|---|---|---|
| Subjects | 4 (PCM + Biology) | 3 (PCM) | 3 (PCB) |
| Questions | 60 | 75–90 (varies) | 180 |
| Marks | 240 | 300 | 720 |
| Time per question | ~3 minutes | ~2.4 minutes | ~1 minute |
| Emphasis | Reasoning across four subjects | Problem-solving speed and depth in PCM | Recall speed and NCERT precision |
The practical implication: a JEE aspirant preparing for IAT usually needs to add Biology; a NEET aspirant usually needs to add Mathematics. Whichever gap you have, it is 60 marks — worth far more attention than another month of polishing your strongest subject.
What a good attempt looks like
A workable plan for the three hours:
- First 10 minutes: scan all four sections quickly and note which questions look immediately doable. IAT rewards this because there is time to spare.
- Next ~100 minutes: clear the doable questions across all four subjects. Do not spend the first hour trapped in one section.
- Next ~50 minutes: attack the harder questions in your two strongest subjects, where a long attempt is most likely to convert.
- Last ~20 minutes: review flagged answers and, importantly, review whether any answer was chosen on a coin-flip. Withdraw the coin-flips.
Practise this shape in every mock so it becomes automatic. The most common IAT mistake is treating the paper like NEET and burning through it in 100 minutes.
Preparation implications
- Prepare four subjects, always. The equal weighting is the defining feature of IAT.
- Practise reasoning questions, not just recall. Assertion-reason and data-interpretation style items reward slow reading.
- Use timed chapter tests to build accuracy at the chapter level first; the free Self Study chapter tests are designed for exactly this.
- Then move to full-length IAT-style mocks with the timing plan above.
- Follow our complete IAT 2027 preparation guide for a month-by-month plan.
If you would rather have that structure supplied and reviewed, the Prepkunj IISER/IAT programme covers all four subjects with live classes, notes and a test series, and our IAT online coaching guide explains what to look for in any programme you consider.
Before you plan anything, verify
Open the current IAT notice and note down four things: the number of questions, the marking scheme, the duration, and the eligibility clause that applies to your board and year. Those four lines are the foundation of your entire plan, and they are the ones most likely to have changed since last year.
Related guides
Frequently asked questions
- What is the IAT exam?
- IAT, the IISER Aptitude Test, is the common computer-based entrance test used for admission to the five-year BS-MS dual degree programme at the Indian Institutes of Science Education and Research. Applications and notices are published on the official IISER admission website.
- What is the IAT exam pattern?
- Recent IAT papers have carried 60 multiple-choice questions, 15 each from Biology, Chemistry, Mathematics and Physics, for 240 marks in a 180-minute computer-based test. Always confirm the current year's pattern in the official notice before planning your attempt.
- What is the IAT marking scheme?
- Recent papers have awarded plus four marks for a correct answer and deducted one mark for an incorrect answer, with no deduction for unattempted questions. That makes accuracy more valuable than attempt count.
- Is Mathematics compulsory in IAT?
- The paper contains a Mathematics section that carries a quarter of the marks, and it is not optional in the way some other exams allow. A candidate who did not study Mathematics in Classes 11 and 12 is therefore at a real disadvantage and should check the current eligibility and paper instructions in the official notice.
- Is IAT harder than NEET or JEE Main?
- IAT is not longer, but it is broader. It spans four subjects instead of three, and its questions lean towards reasoning and concept application rather than volume, so students often find the paper shorter but individual questions more thought-heavy.
- How many questions should I attempt in IAT?
- There is no fixed number. With negative marking and only 60 questions, attempting around 45 to 52 with high accuracy usually produces a better score than attempting all 60 with guesses on eight or ten.
- Can I prepare for IAT along with JEE or NEET?
- Yes, and most successful candidates do. The Physics, Chemistry and Mathematics overlap with JEE Main and the Biology overlap with NEET is substantial, so the extra work is mostly the fourth subject plus IAT-style reasoning practice.
Sources
About the author
Prepkunj Academic Team · Physics, Chemistry, Biology and Mathematics faculty
The Prepkunj Academic Team prepares and maintains every Learning Hub resource using live classroom experience with NEET, JEE, BITSAT, IAT and CBSE students.