IISER Aptitude Test (IAT) — Everything You Actually Need to Know
If you genuinely love science — not just solving exam problems, but actually curious about how things work at a fundamental level — the IISERs are probably the best undergraduate science institutions in India right now. The IAT is the only door in. This guide covers what the exam looks like, how to prepare for it, what scores you realistically need, and what happens after the result.
One thing worth saying upfront: the competition for IAT has changed dramatically in recent years. Since KVPY and the JEE Advanced channel for IISER admission were removed, every aspirant now funnels through one single exam. Participation has roughly tripled compared to a few years ago. If your preparation plan is based on what worked in 2021 or 2022, you are working with outdated information.
What Are IISERs — A Quick Primer
There are seven IISERs — Berhampur, Bhopal, Kolkata, Mohali, Pune, Thiruvananthapuram, and Tirupati. All of them were set up specifically to combine science education with research from the very beginning. Students don't just sit in classrooms; they're in labs and working on real projects from semester one. The faculty mostly hold PhDs from top institutions worldwide, and the environment is genuinely research-oriented in a way that most engineering colleges are not.
The flagship degree is the 5-year BS-MS dual degree in natural sciences, available at all seven campuses. Beyond that, IISER Bhopal offers B.Tech programs in Chemical Engineering, Data Science & Engineering, and Electrical Engineering & Computer Science. IISER Bhopal also has a 4-year BS in Economic Sciences, IISER Tirupati has a 4-year BS in Economic and Statistical Sciences, and IISER Kolkata runs a BS-MS in Computational and Data Sciences. The options are wider than many people assume — it's not only pure science.
Exam Pattern — The Basics
IAT is a computer-based test with exactly 60 questions — 15 each from Biology, Chemistry, Mathematics, and Physics. Total time is 3 hours (180 minutes). Every subject contributes equally; you cannot skip a section or avoid any subject.
| Subject | Questions | Correct Answer | Wrong Answer | Max Marks |
|---|---|---|---|---|
| Biology | 15 | +4 | −1 | 60 |
| Chemistry | 15 | +4 | −1 | 60 |
| Mathematics | 15 | +4 | −1 | 60 |
| Physics | 15 | +4 | −1 | 60 |
| Total | 60 | — | — | 240 |
All questions are MCQ with a single correct option — no integer-type, no paragraph-based questions. An online non-programmable scientific calculator is provided on screen. The question paper comes in English and Hindi. The exam happens at a single national slot, typically starting at 9:00 AM IST on a Sunday in early June.
Eligibility — Who Can Appear
Qualifying Exam and Year of Passing
You must have passed or be currently appearing in Class XII (or an equivalent 3-year diploma from a board recognized by AICTE or COBSE) in the year of the exam or in the immediately preceding two years. The eligibility window is a rolling three-year window — the current year plus the two years before it. If you passed earlier than that, you are not eligible.
The "passing year" means the year your result was first declared as pass — not the year you improved a subject. So if you cleared Class XII in one year and improved a subject the next year, your passing year is still the earlier one for eligibility purposes.
Subjects Required
For the BS-MS science program at any IISER, you need at least three of the four IAT subjects (Biology, Chemistry, Mathematics, Physics) in your Class XII. For the B.Tech programs, BS in Economic Sciences, BS in Economic and Statistical Sciences, and the Computational and Data Sciences BS-MS, you specifically need Mathematics in your qualifying exam.
Minimum Marks in Class XII
| Category | Minimum Aggregate |
|---|---|
| General / OBC-NCL / EWS | 60% |
| SC / ST / PwD | 55% |
This percentage is calculated across all subjects you took — not just the best five or the science subjects alone. All subjects count toward the aggregate.
Application — What to Expect Each Year
The application portal typically opens in the first week of March and closes in mid-April. There is usually a correction window of about 3 days after the deadline to fix minor errors. However, category selection cannot be changed even in that window — so be careful the first time.
| Candidate Category | Application Fee (approx.) |
|---|---|
| General / EWS / OBC / OBC-NCL | ₹2,000 |
| SC / ST / PwD / Kashmiri Migrants | ₹1,000 |
| Foreign Nationals | ₹12,000 |
The application fee is non-refundable. Applications must be submitted only through the official IISER admission website — www.iiseradmission.in. No third-party portals are valid.
Typical Annual Schedule
| Event | Typical Timing |
|---|---|
| Application portal opens | First week of March |
| Application deadline | Second week of April |
| Correction window | Third week of April (2–3 days) |
| Hall ticket release | Last week of May |
| Exam date | First Sunday of June |
| Answer key release | Same day as exam |
| Objection filing window | 2–6 days after exam |
| Document upload deadline | ~2 weeks after exam |
| Result declaration | Late June or early July |
| Counselling and seat allotment | July–August |
Always verify exact dates on the official website for the current year. The schedule above reflects the consistent pattern across multiple cycles but specific dates shift slightly each time.
Documents to Keep Ready
Class X marksheet, Class XII marksheet (or a signed declaration if the result isn't out yet), caste and category certificates where applicable, PwD certificates if relevant, and a photo ID. All scanned copies need to be between 200KB and 1MB. If the Class XII result isn't out when you apply, you can upload a declaration and submit the actual marksheet later — but missing that upload deadline disqualifies you from seat allocation.
Seat Matrix — How Many Seats and Where
| Institute & Program | Approximate Seats |
|---|---|
| IISER Berhampur – BS-MS | ~300 |
| IISER Bhopal – BS-MS | ~300 |
| IISER Kolkata – BS-MS | ~280 |
| IISER Kolkata – BS-MS (Computational & Data Sciences) | ~30 |
| IISER Mohali – BS-MS | ~275 |
| IISER Pune – BS-MS | ~288 |
| IISER Thiruvananthapuram – BS-MS | ~320 |
| IISER Tirupati – BS-MS | ~250 |
| IISER Bhopal – B.Tech Chemical Engineering | ~40 |
| IISER Bhopal – B.Tech Data Science & Engineering | ~80 |
| IISER Bhopal – B.Tech EECS | ~75 |
| IISER Bhopal – BS Economic Sciences | ~55 |
| IISER Tirupati – BS Economic & Statistical Sciences | ~50 |
| Total | ~2,343 |
Seat numbers are subject to minor changes each year. With over 2 lakh candidates competing for roughly 2,300 seats, the success rate is around 1 in 100. It's genuinely competitive.
Reservation Breakdown
| Category | Reservation |
|---|---|
| SC | 15% |
| ST | 7.5% |
| OBC-NCL | 27% |
| GEN-EWS | 10% |
| PwD (horizontal, within each category) | 5% |
| Kashmiri Migrants (supernumerary) | 3 seats per IISER |
Fee Structure — After You Get a Seat
The application fee is separate from the Seat Acceptance Fee (SAF), which you only pay after receiving an admission offer. The SAF holds your seat.
| Category | SAF Amount | Non-refundable Part |
|---|---|---|
| General / EWS / OBC / OBC-NCL / PwD / KM | ₹35,000 | ₹10,000 |
| SC / ST | ₹17,500 | ₹5,000 |
The SAF is adjusted against your first semester fees once you register at the IISER. If you withdraw before the Round-wise Withdrawal deadline, the full SAF minus nothing is returned. If you withdraw after that deadline but before the Final Withdrawal deadline, ₹10,000 is deducted (₹5,000 for SC/ST). After the Final Withdrawal deadline, that particular IISER's own refund policy applies.
Complete Syllabus
The IAT syllabus is Class XI + Class XII NCERT across all four subjects. It follows the CBSE/NCERT framework and does not include anything beyond it. There are no JEE-specific advanced topics that go outside this boundary. That said, the questions are applied — they test whether you actually understand the concepts, not just whether you can recall them.
Physics
Units & Measurements, Motion in a straight line and a plane (projectile, circular), Laws of Motion (Newton's laws, conservation of momentum), Work-Energy-Power (potential energy, collisions), Rotational Motion (moment of inertia, angular momentum), Gravitation (Kepler's laws, satellites, escape velocity), Properties of Solids and Fluids (Bernoulli, viscosity, surface tension), Thermodynamics (laws, Carnot engine), Kinetic Theory, Oscillations (SHM, pendulum), Waves (superposition, beats), Electrostatics (Coulomb's law through Gauss's law, capacitance), Current Electricity (Ohm's law, Kirchhoff's laws, Wheatstone bridge), Magnetism (Biot-Savart, Ampere's law, torque on current loops), Electromagnetic Induction (Faraday, Lenz, inductance), Alternating Current (LCR circuits, transformers), Electromagnetic Waves, Ray Optics (mirrors, lenses, prisms), Wave Optics (Young's double slit, diffraction, polarisation), Dual Nature of Radiation (photoelectric effect, de Broglie), Atoms (Bohr model), Nuclei (radioactivity, binding energy), Semiconductor Electronics (p-n junction, rectifier).
Chemistry
Basic Concepts (mole concept, stoichiometry, empirical formula), Atomic Structure (Bohr model, quantum mechanical model), Periodic Table and Periodicity, Chemical Bonding (VSEPR, hybridisation, Molecular Orbital Theory, hydrogen bonding), Thermodynamics (enthalpy, Gibbs energy, spontaneity), Chemical and Ionic Equilibrium (buffer solutions, solubility product), Redox Reactions, Solutions (colligative properties, Raoult's law), Electrochemistry (Nernst equation, electrolysis, batteries), Chemical Kinetics (rate laws, Arrhenius equation), Organic Basics and Reaction Mechanisms (inductive, resonance, nucleophilic/electrophilic reactions), Hydrocarbons, Haloalkanes and Haloarenes, Alcohols/Phenols/Ethers, Aldehydes/Ketones/Carboxylic Acids, Nitrogen Compounds (amines, diazonium salts), Biomolecules (carbohydrates, proteins, nucleic acids), d & f Block Elements, Coordination Compounds (Werner's theory, nomenclature, isomerism, bonding).
Mathematics
Sets, Relations & Functions (types, composition, inverse), Complex Numbers (Argand plane, modulus, polar form), Quadratic Equations, Linear Inequalities, Permutations & Combinations, Binomial Theorem, Sequences & Series (AP, GP, special sums), Trigonometry (identities, equations, inverse trig functions, graphs), Coordinate Geometry — 2D (straight lines, circles, parabola, ellipse, hyperbola), 3D Geometry (direction cosines, equations of lines and planes, shortest distance), Matrices and Determinants (operations, inverse, area of triangle, solving systems), Limits and Continuity, Differentiation (chain rule, implicit, parametric, logarithmic; second-order), Applications of Derivatives (tangents, normals, maxima-minima, rate of change), Integration (substitution, partial fractions, integration by parts, definite integrals), Applications of Integration (area under curves), Differential Equations (variable separable, homogeneous, linear first-order), Vectors (dot and cross products, projection), Statistics (mean deviation, variance, SD), Probability (conditional probability, Bayes' theorem, independent events).
Biology
Diversity of Living World (classification, kingdoms — Monera through Animalia, plant and animal kingdoms), Morphology and Anatomy of Flowering Plants, Cell Biology (prokaryotic vs eukaryotic cells, organelles, cell cycle, mitosis and meiosis), Biomolecules (proteins, polysaccharides, nucleic acids, enzymes), Plant Physiology (photosynthesis including light reactions, Calvin cycle, C4 pathway; respiration — glycolysis, Krebs cycle; plant growth regulators), Human Physiology (breathing and gas exchange, blood and circulation, excretion, locomotion and joints, neural control, endocrine system), Reproduction in Flowering Plants and Humans (gametogenesis, fertilisation, embryonic development), Genetics (Mendel's laws, sex determination, mutation, molecular basis — DNA replication, transcription, translation, gene expression regulation), Evolution (Hardy-Weinberg principle, natural selection, speciation), Human Health and Disease (immunity, AIDS, cancer), Microbes in Human Welfare, Biotechnology (recombinant DNA technology, applications in agriculture and medicine), Ecology (population interactions, energy flow, ecological pyramids, biodiversity conservation).
Cut-offs, Scores and Rank Analysis
Official cutoffs change every year and are released only after results. But the trends across multiple years give a fairly reliable picture of what to aim for.
Marks vs Rank — General Category Reference
| Score Range (out of 240) | Approximate Rank | Likely Outcome |
|---|---|---|
| 200 and above | Top 80–100 | Any IISER; also competitive for IISc BS Research |
| 175–199 | ~200–500 | IISER Pune, Kolkata comfortable in early rounds |
| 150–174 | ~500–1,500 | IISER Bhopal, Mohali, Thiruvananthapuram strong |
| 130–149 | ~1,500–4,000 | Berhampur, Tirupati likely; others possible in later rounds |
| 110–129 | ~4,000–8,000 | Newer IISERs in later rounds; reserved categories more competitive |
| Below 110 | 8,000+ | Uncertain — heavily depends on that year's competition level |
One important pattern worth noting: rank inflation is real. When a particular year's paper is easier, average scores jump across the board and a score that would have placed you in the top 1,000 the previous year might land you at 4,000+. This happened noticeably in recent cycles. The practical lesson is don't target the minimum — aim for 150+ to have a comfortable safety margin regardless of how the paper turns out.
Campus-wise Approximate Closing Ranks (General Category)
| IISER Campus | Approx. Closing Rank (General) | Remarks |
|---|---|---|
| IISER Pune | Under ~750 (by final round) | Most competitive — oldest and most prestigious campus |
| IISER Kolkata | ~800–1,100 | Strong Physics and Chemistry departments |
| IISER Bhopal | ~1,000–1,600 | B.Tech programs push demand higher |
| IISER Mohali | ~1,200–2,000 | Well-established research culture |
| IISER Thiruvananthapuram | ~1,500–2,800 | Good option for mid-range ranks |
| IISER Tirupati | ~2,000–4,500 | Newer campus; closing rank is higher (more accessible) |
| IISER Berhampur | ~2,500–5,000+ | Newest campus; most accessible for lower ranks |
Other Institutions That Accept IAT Scores
IAT is not only for IISERs. These institutions also use IAT scores for admission to their own programs — but you must apply to each of them separately. The IISER application alone does not register you there.
| Institution | Program |
|---|---|
| IISc Bengaluru | 4-year BS (Research) |
| IIT Madras | 4-year BS |
| IIT Guwahati | 4-year BS in Biomedical Science & Engineering |
| IACS Kolkata | Integrated BS-MS |
| IIEST Shibpur | 5-year BS-MS in Chemistry, Physics & Applied Geology |
IISc Bengaluru is the most coveted of these — getting in generally requires a score in the 200+ range. IACS and IIEST Shibpur tend to have somewhat lower thresholds. Always check each institute's own website for eligibility criteria, which can differ from IISER's requirements.
The Admission Process — How It Works After Results
After results are declared, qualified candidates (those who receive a rank) register for counselling on the IISER portal. At that point, you submit a preference list ranking all available academic programs across all seven IISERs in order of preference. There are around 13 programs to choose from. You only get considered for programs on your list — if you don't include a campus, you simply won't be offered a seat there even if your rank qualifies.
Seat allocation happens in multiple rounds. When you receive an offer, you have two choices. FREEZE means you accept the seat and the counselling ends for you. FLOAT means you accept the seat tentatively but stay in subsequent rounds hoping for something higher on your preference list. If nothing better opens, you keep the current offer. But if you reject an offer entirely — or miss the payment deadline for the Seat Acceptance Fee — you exit the process permanently with no re-entry.
The entire counselling process is online. You don't need to visit any campus during this stage. Physical document verification and reporting happen later at the allotted IISER on a joining date announced by that campus.
Previous Year Question Papers
Practicing actual past papers is probably the single most useful thing you can do besides covering the syllabus. IAT has a distinctive question style — it doesn't ask you to recall facts directly, it presents a scenario and asks what follows from it. Biology questions in particular require applying concepts to situations you haven't seen before. Past papers are the only way to calibrate for this.
Easier overall. Bio and Chemistry were noticeably simpler. Caused significant rank inflation — a good lesson on why targeting the minimum score is risky.
Download PDF [add link]First year after KVPY removal. Harder than expected. The best benchmark paper for testing your concept depth.
Download PDF [add link]Last year when KVPY and JEE Advanced channels existed alongside IAT. Moderate difficulty. Good for understanding question style.
Download PDF [add link]Solid paper from before the competition surge. Useful as a baseline to understand the original IAT format and tone.
Download PDF [add link]Post-COVID year. Good for practicing Biology and Chemistry conceptual questions which have remained consistent in style.
Download PDF [add link]One of the earlier papers. Useful for understanding how the exam was conceived before participation exploded.
Download PDF [add link]Mock tests are also released on the official website (www.iiseradmission.in) each year before the exam. Use them — the interface is exactly what you'll see on exam day.
Preparation Strategy — What Actually Works
NCERT First, Everything Else Second
Every IAT question is rooted in NCERT concepts. Not NCERT exemplar problems, not HC Verma advanced chapters — the core NCERT text. For Biology, NCERT is the primary resource because question language often mirrors it directly. For Physics and Chemistry, NCERT gives the conceptual base and standard JEE problem-solving develops the application layer on top of it.
Don't Underestimate Biology
This is the most common strategic mistake, especially among PCM students who didn't take Biology in Class XII. That's 15 questions worth 60 marks. Scoring 11 correct in Biology versus 4 correct is a rank difference of thousands. The Biology syllabus is conceptually detailed but not mathematically difficult — it rewards careful reading more than calculation. Budget at least 20–25% of your total preparation time for it.
On Negative Marking
Physics — Understand the Physics, Not Just the Formula
IAT Physics is concept-heavy. Questions often describe a novel physical situation and ask you to reason from first principles. Memorising formulas without knowing what they represent will fail you. Electrostatics, Optics, and Modern Physics (atoms, nuclei, semiconductors) have historically appeared frequently and are worth extra attention.
Mathematics — Don't Skip Calculus or Probability
Calculus, Vectors, 3D Geometry, and Probability together account for a large chunk of Math questions. These are areas where JEE preparation sometimes has gaps because certain NCERT topics (differential equations, 3D geometry details, Bayes' theorem) get deprioritised for JEE but appear in IAT. Cover them properly.
Chemistry — Organic Mechanisms and Equilibrium Are Central
Organic reaction mechanisms, Electrochemistry, Chemical Kinetics, and both chemical and ionic equilibrium are consistently tested. For Inorganic Chemistry, d-block elements and coordination compounds are high-yield. NCERT Inorganic gets underestimated because JEE coaching often handles it superficially — read it yourself, carefully.
On the Day of the Exam
Candidates must report by 7:00 AM. Entry closes at 8:30 AM — no exceptions for latecomers. Carry the printed Hall Ticket (A4 size, laser print recommended) with your photograph pasted on it, plus one original valid photo ID — Aadhaar, Passport, PAN card, Voter ID, Driving Licence, or a 10th/12th marksheet with photograph. The photo on the ID must be clearly visible and match the name on the Hall Ticket.
No mobile phones, smart watches, or personal calculators are allowed inside the hall. The only permitted items are the Hall Ticket, original photo ID, a transparent water bottle, and a ball pen. Rough sheets are provided and must be returned to the invigilator after the exam.
The exam centre may not always be in your preferred city — JAC allocates centres based on availability and can assign you to a different city. Requests for centre changes are not entertained, so plan your travel and accommodation with this uncertainty in mind.
PwD Provisions
Candidates with at least 40% disability can avail scribe assistance (if needed) and one hour of compensatory extra time. Candidates with less than 40% disability who have documented difficulty with writing can also avail both a scribe and compensatory time, per a Supreme Court directive. These must be opted for during the application process — they cannot be requested later. If a candidate avails scribe services without being eligible, the consequences include disqualification and cancellation of admission even if already enrolled at an IISER.
Final Thoughts
The IISERs genuinely offer something different. If you want to understand science deeply and eventually contribute to research, these campuses are among the best environments in India for it — the faculty access, the lab exposure from year one, the peer group, and the research opportunities are all calibrated for students who want to think seriously about science, not just pass exams.
The IAT has gotten harder to crack because the competition has intensified, not because the exam itself has fundamentally changed. The questions still reward understanding over rote preparation. That means a student who genuinely knows the concepts and can apply them will consistently outperform a student who has memorised more but understood less. Cover all four subjects, do past papers under real time pressure, and don't make the Biology mistake. That's most of the strategy.
For the most current information on dates, fees, and seat matrix, always check the official website: www.iiseradmission.in. Numbers here reflect recent cycles and the structure remains stable, but small details change annually.
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