ISRO Scientist Exam Pattern 2026: CBT, Marking and Interview

The ISRO Scientist exam pattern decides how you spend every minute of the written test for Scientist/Engineer 'SC', the entry-level technical post at the Indian Space Research Organisation. Under Advertisement No. ISRO:ICRB:03(EMC):2026, the ISRO Centralised Recruitment Board (ICRB) selects candidates in Electronics, Mechanical and Computer Science through a computer-based test (CBT) and an interview. The CBT is scheduled for 29 October 2026.

This page explains both stages in detail: the two parts of the written test, the marking scheme, the qualifying marks, the interview break-up and how the final merit list is calculated, with a worked example. It also turns the numbers into a practical time plan, so you know where marks are won and lost before you sit the test.

Table of Contents

• ISRO Scientist Exam Pattern at a Glance

• Key Changes to Know

• Written Test Pattern

• Marking Scheme and Negative Marking

• What the Pattern Means for You

• Qualifying Marks and Interview Shortlisting

• Interview Pattern

• Final Merit Calculation

• CBT Route vs GATE Route

• Exam-Day Time Plan

• How to Practise in the Current Pattern

ISRO Scientist Exam Pattern 2026 at a Glance

Selection has only two stages. There is no physical test, typing test or descriptive paper, so your written score and your interview performance together decide the result.

Key Changes to Know

• The test is now computer-based: The official 2025 paper was a pen-and-paper OMR test. The 2026 advertisement calls the written test a CBT, so practise reading and answering on screen.

• Part B has at most 15 questions: The aptitude section carries 20 marks but a maximum of 15 questions. Some pages still show 20 questions, which is outdated.

• Only three disciplines in this CBT: Electronics (BE001), Mechanical (BE002) and Computer Science (BE003), plus one post in each at the Physical Research Laboratory (PRL). Other branches were recruited through a separate GATE-score advertisement.

• Revised test date: The CBT was moved from 19 October 2026 to 29 October 2026.

ISRO Scientist Written Test Pattern

The written test has two parts with separate time limits. Part A tests your own engineering discipline, and Part B tests general aptitude. Both are multiple-choice.

Part A: Discipline-Specific Section

Part A is set from the core subjects of the discipline you applied for. Each question carries one mark. ISRO does not publish a topic-wise syllabus, but its previous papers show a strong overlap with the undergraduate curriculum and the GATE syllabus of each branch.

Part B: Aptitude and Ability Section

Part B covers numerical, logical, diagrammatic, abstract and deductive reasoning. It is common to all three disciplines. With 20 marks spread over at most 15 questions, each question is worth about 1.33 marks if all 15 are asked, more than any single Part A question.

Exam Language and Test Centres

The 2026 advertisement does not state the medium of the question paper. ISRO's published 2025 papers were bilingual, in English and Hindi, so expect the same unless the CBT instructions say otherwise. The test is held in 37 cities, including Agartala, Ahmedabad, Bengaluru, Bhopal, Chennai, Delhi, Guwahati, Hyderabad, Jaipur, Kolkata, Lucknow, Mumbai, Patna, Port Blair, Pune and Thiruvananthapuram. Your centre is fixed by the city you chose in the application, and ISRO does not pay travel allowance for the written test.

ISRO Scientist Marking Scheme and Negative Marking

A quick example shows how this works. Suppose you attempt 60 questions in Part A and get 48 right and 12 wrong. Your Part A score is 48 minus 4 (12 x 1/3), which is 44 out of 80. If you also answer 12 of 15 Part B questions correctly, you add about 16 marks, for a total near 60 out of 100.

What the Pattern Means for You

• Part A decides most of your score: It carries 80 of the 100 marks, so most of your preparation time belongs to your core subjects.

• Three wrong answers cancel one right answer: In Part A, 12 careless errors cost you 4 full marks. Accuracy matters more than the number of attempts.

• Blind guessing does not pay, but smart guessing can: If a question has four options, a pure guess has an expected value of zero. If you can rule out even one option, the expected value turns positive, so a guess between three options is worth taking.

• Attempt every Part B question: There is no penalty and each question is worth more than one mark. Leaving a Part B question blank is the costliest mistake in the paper.

• The clock is tight in Part A: 90 minutes for 80 questions gives you about 67 seconds per question. Numerical problems need a fast first pass and a planned return.

Qualifying Marks and Interview Shortlisting

Clearing the written test is a two-step filter. You must first reach the minimum qualifying marks, and then rank high enough to be called for interview.

• Qualifying is not the same as shortlisting: Scoring 50 out of 100 only makes you eligible for consideration. Candidates are called for interview in a 1:5 ratio to vacancies, with at least 10 candidates for each post.

• Previous cut-offs sit near the qualifying line: For the 2023 advertisement, ISRO's published written test cut-offs (other than PwBD) were 49.00 in Electronics, 55.04 in Mechanical and 51.37 in Computer Science. Treat these as a benchmark only and aim for a clear margin above them.

ISRO Scientist Interview Pattern

The interview carries 100 marks and is assessed on five parameters listed in the advertisement.

Technical knowledge carries 40 marks, so revise your core subjects and final-year project again after the CBT. Candidates who are employed must produce a No Objection Certificate (NOC) from their employer at the interview, or they are not allowed to appear.

ISRO Scientist Final Merit Calculation

The final panel gives 50% weightage to written test marks and 50% to interview marks. Both are out of 100, so your final score is simply the average of the two, as long as you clear every minimum.

The examples show that a strong written score cannot rescue a weak interview, because each stage has its own minimum. Candidate C, with a lower written score than Candidate B, finishes ahead after a solid interview.

ISRO Scientist CBT Route vs GATE Route

ISRO used two different selection methods for Scientist/Engineer 'SC' in 2026. Many pages mix them up, so check which advertisement you are preparing for.

Exam-Day Time Plan

The advertisement gives Part A 90 minutes and Part B 30 minutes. Read the on-screen instructions on the day to see whether time can be carried between parts. A plan that works within the official split:

Practise this split in full-length mocks so the timing feels natural before 29 October. A timed ISRO Scientist test series on Testkart lets you rehearse the 90 and 30-minute blocks on screen and compare your attempts and accuracy across tests.

How to Practise in the Current Pattern

• Start with official papers: ISRO has published the 2023 and 2025 papers for all three disciplines on its recruitment page. Solve them under timed conditions to judge the real difficulty level.

• Take sectional tests for Part B: Diagrammatic and abstract reasoning are not part of standard engineering preparation, so practise them on their own.

• Track your negative marks: After each mock, note how many marks you lost to wrong answers in Part A and set a personal rule for when to skip.

• Simulate the CBT: Since the 2026 test is on screen, practise on a computer rather than on paper.

Older pages may still show 20 questions in Part B or older dates and disciplines, so follow the official notification. Check the official ICRB recruitment page and the Advertisement ISRO:ICRB:03(EMC):2026 for any change before the test.