What is CDS

Tri-Defence Services in Indian Forces in which entry is provided after graduation through an entrance exam, which is popularly known as Combined Defence Services or in short CDS. Any Indian who fulfils the eligibility criteria & other terms is eligible to join in any one of the Indian Forces i.e. Army, Navy or Air Force. CDS offers a good career opportunity & great chance to serve the defence forces & the nation.

CDS Exam – CDS exam is conducted on national level twice a year by UPSC – Union Public Service Commission. CDS Exam is comprised of mainly three stages (Four stages for Air Force). All these stages of selection procedure are mentioned below.


  • Written Exam
  • 5 Days Interview by SSB
  • Medical Fitness Test

For Air Force – AFA

  • Written Exam
  • 5 Days Interview by SSB
  • Computerized Pilot Selection System Test – CPSS
  • Medical Fitness Test

Training – After clearing the above tests, finalized candidates are called for the training in concern branch as given below.

  • Indian Military Academy, Dehradun – Candidates finally selected will undergo a course of training for about 18 months. Candidates will be enrolled under the Army Act as Gentlemen cadets.
  • Indian Naval Academy, Ezhimala – The duration of training at INA, Ezhimala for Naval Orientation Course will be 74 weeks. The cadets shall be commissioned after successful completion of approximately 18 months of training.
  • Air Force Academy, Hyderabad – The approximate duration of training for Flying Branch (Pilots) at the Air Force Academy will be 74 weeks.
  • Officers’ Training Academy, Chennai – Finally selected candidates will undergo a course of training at the Officers Training Academy, for an approximate period of 49 weeks. Candidates will be enrolled as Gentlemen/Lady Cadets.

Fixed Stipend for cadet Training – Stipend to Gentlemen or Lady Cadets during the entire duration of training in Service academies i.e. during training period at IMA and OTA is Rs 56,100/- p.m.* (Starting pay in Level 10) while AFA cadets will get 21000 as fixed Stipend which includes 15,600/- as pay in Pay Band plus Grade Pay of 5,400/- for the entire duration of training.

Rank awarded after successful training of cadets – On successful completion of training Gentlemen Cadets are granted Permanent Commission in the rank of Flying Officer in Air Force, Lieutenant in Army, Sub-Lieutenant in Navy and Short Service Commission at the rank of Lieutenant thru OTA.

What is CDS Eligibility Criteria?

As you are planning to join Indian Army, Navy & Air Force after graduation by clearing CDS Written Exam, SSB Interview & Medical fitness test, then you must check all of the eligibility criteria laid down by UPSC & Indian Army, Navy & Air Force. For your ease, we have summarized all important details like qualification, age, percentage, Physical & Visual Standard below.


  1. a Citizen of India, or
  2. a subject of Bhutan, or
  3. a subject of Nepal, or
  4. a Tibetan refugee who came over to India before the 1st January, 1962 with the intention of permanently settling in India, or
  5. a person of Indian origin who has migrated from Pakistan, Burma, Sri Lanka and East African Countries of Kenya, Uganda, the United Republic of Tanzania, Zambia, Malawi, Zaire and Ethiopia or Vietnam with the intention of permanently settling in India.


  • For Indian Military Academy (IMA) age limit is between 19 to 24 years
  • For Indian Naval Academy (INA) age limit should be between 19 to 22 years
  • For Indian Air Force Academy (AFA) age limit should be between 20 to 24 years
  • For Officer’s Training Academy the age limit is 19 to 25 years.

Note: The date of birth accepted by the Commission is that entered in the Matriculation/Secondary School Examination Certificate or in a certificate recognised by an Indian University as equivalent.


  1. For I.M.A. and Officers’ Training Academy, Chennai — Degree of a recognized University or equivalent.
  2. For Indian Naval Academy—Degree in Engineering from a recognized University/Institution.
  3. For Air Force Academy—Degree of a recognised University (with Physics and Mathematics at 10+2 level) or Bachelor of Engineering.

Note: Graduates with first choice as Army/Navy/Air Force are to submit proof of Graduation/provisional certificates on the date of commencement of the SSB Interview at the SSB.

Final Year Students – Candidates who are studying in the final year/semester Degree course and have yet to pass the final year degree examination can also apply.

Marital Status

  • For Indian Military Academy, applicants should be- Unmarried
  • For Indian Naval Academy, applicants should be- Unmarried
  • For Air Force Academy, applicants should be- Unmarried
  • For Officers Training Academy (SSC Men) applicants should be- Unmarried
  • For Officers Training Academy (SSC Women Non-Technical courses)- Unmarried or issueless widowed or issueless divorcees who didn’t remarried

Physical Standard

Candidates must be physically fit according to physical standards for admission to Combined Defence Services Examination as per guidelines.

  1. The candidate must be in good physical and mental health and free from any disease/disability which is likely to interfere with the efficient performance of duties.
  2. There should be no evidence of weak constitution, bodily defects or underweight. The candidate should not be overweight or obese.
  3. The minimum acceptable height for male candidates is 157.5 cms. (157 cms for Navy and 162.5 cms for Air Force). For Women candidates minimum acceptable height is 152 cms. For Gorkhas and individuals belonging to hills of North-Eastern region of India, Garhwali and Kumaon, the Minimum acceptable height will be 5 cms less. In case of candidates from Lakshadweep, the minimum acceptable height can be reduced by 2 cms.
  4. The candidates should have sufficient number of natural and sound teeth. A minimum of 14 dental points will be acceptable. When 32 teeth are present, the total dental points are 22. A candidate should not be suffering from severe pyorrhoea.

Note: These concessions are not applicable for Air Force.

Physical Conditioning: Prospective candidates are advised to keep themselves in good physical condition by following the under mentioned routine :—

  1. Running : 2 to 4 Km. in 15 minutes
  2. Skipping
  3. Pushups & Sit-ups : Minimum 20 each
  4. Chin ups : Minimum 08
  5. Rope Climbing : 3 to 4 metres.

Visual Standard

Visual Standards for Army

Vision (corrected) better eye 6/6 and worse eye 6/12Vision(corrected) better eye 6/6, worse eye 6/12
Myopia of not more than minus 3.5 DMyopia of not more than minus 5.5 D
Manifest hypermetropia of not more than plus 3.5 D including AstigmatismManifest hypermetropia of not more than plus 3.5 D including Astigmatism.

Visual Standards for Navy

  • Uncorrected without glass – 6/12
  • Corrected with glass – 6/6
  • Limits of Myopia – 1.5
  • Limits of Hypermetropia +1.5

Visual Standards for Indian Air Force

  • One must have 6/6 in one eye and 6/9 in other, which can be correctable to 6/6 only for hypermetropia.
  • Near Vision must be N-5 each eye


While preparing for CDS exam students must go through some of information which is very important for starting CDS preparation. Knowing the CDS exam pattern will be helpful to give students a brief idea on what they should study & from which subjects & topic the questions in CDS exams are asked.

CDS Exam is a pen & paper based i.e. offline mode of exam in which MCQ – only Objected Type Questions are asked. There are 3 papers conducted in 3 shifts back to back on same day. The three papers are Math, English & GK Subjects from which the questions are asked. Those students who want to join IMA, INA & AFA have to clear all 3 papers with minimum qualifying marks & those who want to join OTA have to clear only 2 papers i.e. English & GK. Detailed CDS exam pattern with no. of questions, full marks & total timing are given below.

  • For IMA, INA & AFA
PaperTotal QuestionMarksDuration
English1201002 Hours
General Ability1201002 Hours
Maths1001002 Hours
  • For OTA
PaperTotal QuestionMarksDuration
English1201002 Hours
General Ability1201002 Hours
  • Negative Marking Scheme: ⅓ of the marks will be deducted for each of the wrong answer.
  • Question Paper Language: The question papers (Test Booklets) of General Knowledge and Elementary Mathematics will be set bilingually in Hindi as well as English.
  • Question Type: The papers in all the subjects will consist of objective type questions only.

CDS Written Exam Syllabus

For CDS Written exam preparation, students need to prepare 3 subjects – Maths, English & GK. Those who are preparing for IMA, INA & AFA have to appear in the tests of all these three subjects but those who are targeting OTA, have to appear in only two tests i.e. English & GK.

Standard of Questions – The standard of the papers in Elementary Mathematics will be of Matriculation level. The standard of papers in other subjects will approximately be such as may be expected of a graduate of an Indian University.

Below, we are mentioning the complete syllabus for CDS written exam.


  • Basic Grammar Topics
  • Comprehension
  • Synonyms
  • Antonyms
  • Para Jumbles
  • Error Spotting


  • Current events, daily news paper headlines, chemistry, history, geography etc.
  • General Knowledge including knowledge of current events and of such matters of everyday observation and experience in their scientific aspects as may be expected of an educated person who has not made a special study of any scientific subject.
  • The Paper will also include questions on History of India and Geography of a nature which Candidate should be able to answer without special study.


  • Arithmetic
    • Number System—Natural numbers, Integers, Rational and Real numbers. Fundamental operations, addition, subtraction, multiplication, division, Square roots, Decimal fractions.
    • Unitary method, time and distance, time and work, percentages, applications to simple and compound interest, profit and loss, ratio and proportion, variation.
    • Elementary Number Theory—Division algorithm. Prime and composite numbers. Tests of divisibility by 2, 3, 4, 5, 9 and 11. Multiples and factors.
    • Factorisation Theorem. H.C.F. and L.C.M. Euclidean algorithm. Logarithms to base 10, laws of logarithms, use of logarithmic tables.
  • Algebra
    • Basic Operations, simple factors, Remainder Theorem, H.C.F., L.C.M. Theory of polynomials, Solutions of quadratic equations, relation between its roots and coefficients (Only real roots to be considered).
    • Simultaneous linear in equations in two variables and their solutions. Practical problems leading to two simultaneous linear equations or in equations in two Variables or quadratic equations in one variable & their solutions.
    • Set language and set notation, rational expressions and conditional identities, Laws of indices.
  • Trigonometry
    • Sine x, cosine x, Tangent x when 0 ≤x ≤90 Values of sin x, cos x and tan x, for x = 0o, 30o, 45o, 60o and 90o
    • Simple trigonometric identities,
    • Use of trigonometric tables,
    • Simple cases of heights and distances.
  • Geometry
    • Lines and angles, Plane and plane figures, Theorems on
      • Properties of angles at a Point,
      • Parallel lines,
      • Sides and angles of a triangle,
      • Congruency of triangles,
      • Similar triangles,
      • Concurrence of medians and altitudes,
      • Properties of angles, sides and diagonals of a parallelogram, rectangle and square,
      • Circles and its properties including tangents and normal,
      • Loci.
  • Mensuration
    • Areas of squares, rectangles, parallelograms, triangle and circle. Areas of figures which Can be split up into these figures (Field Book), Surface area and volume of cuboids, lateral surface and volume of right circular cones and cylinders, surface area and Volume of spheres.
  • Statistics
    • Collection and tabulation of statistical data, Graphical representation, frequency Polygons, histograms, bar charts, pie charts etc. Measures of central tendency.

What is CDS Selection Process?

CDS exam selection procedure consists of Written Exam, Interview/ Intelligence Test/ Personality Test, Document Verification, Medical Examination. Here is a detailed UPSC CDS exam selection procedure.

Written Exam

  1. Written Exam consists of Objective Type questions and time duration 2hrs and maximum marks is 100 for each subject.
  2. For the candidates who are appearing for Indian Military Academy, Naval Academy, Air force Academy written test comprising of English, General Knowledge and Elementary mathematics subjects and for candidates who are appearing for officers training academy the written test comprising of English and General Knowledge.
  3. Candidates who are declared successful in the written exam will be detailed for intelligence and personality test at the Service Selection Board based on their preference, by the respective service HQ.

Interview/ Personality Test

The candidates who are selected in written test are called for interview. The SSB procedure consists of two stage selection process-Stage I and Stage II. Only those candidates who clear the stage I are permitted to appear for Stage II.

  1. Stage I comprises of Officers Intelligence Rating (OIR) tests are Picture Perception Description Test (P&DT). The candidates will be shortlisted based on combination of performance in QIR Test and PP and DT.
  2. Stage II comprises of Interview, Group Testing Officers Tasks, Psychology Tests and the conference. These tests are conducted over 4 days.

The personality of candidate is assessed by three different assessor’s viz. the interviewing Officer (IO), Group Testing Officer (GTO) and the Psychologist. There are no separate weightage for each test. The marks are allotted by assessors only after taking into consideration the performance of the candidate holistically in the entire test.

Document Verification

Document Verification will be conducted only after the candidate has qualified for Interview/Personality Test.

Medical Examination

A Candidate recommended by the Services Selection Board for CDS Exam Selection will undergo a medical examination by a Board of Service Medical Officers. Women candidates will undergo Medical Examination by a Medical Board comprising male/ female doctors/ specialists/ Gynaecologist. There will be a Lady Medical Officer as member of Board. Only those candidates will be admitted to the Academy who are declared fit by the Medical Board.

Final Merit List: On the basis of marks of Written Exam and SSB Interview, candidates will be selected for the limited number of vacancies.

CDS Study Plan

Clearing CDS exam is all about a study plan. When you decide that you will join the Indian Defence Forces after your graduation, then you plan for CDS. For CDS preparation, what come in your mind, simply either you starting preparing by self or you join any coaching institute. Even most of the coaching institutes don’t offer the exact & well structured study plan. But we want to stop you here for few minutes only to read this article for the best strategy to prepare you for the CDS written exam. So before moving ahead, we want to brief a summary about CDS.

Combined Defence Services Exam is a national level competitive exam which is conducted by UPSC for recruitment into Indian Military Academy, Indian Naval Academy, Air Force Academy and Officers Training Academy. To read more about CDS exam.

It offers another crucial chance for all those aspirants who have completed their graduation in distinct branches. It is the next opportunity for the candidates after NDA, which offers an exciting career in defence services – IMA, INA, AFA & OTA on the graduation basis. UPSC conducts CDS Written Exam twice a year, Generally CDS I exam is conducted in month of February & CDS II is conducted in month of September or in November. Next CDS written exam will be held on Sunday, 2nd February, 2020.

Now come to the point how to crack CDS or CDS study plan. We are summarized this important topic into 6 points. So read out the 6 key points for the best preparation of CDS.

  1. Exam Pattern & Syllabus: We just want to give a reminder on these things because you must be aware of CDS exam pattern & CDS syllabus. But before moving ahead kindly makes sure that there is not change in the CDS exam pattern & syllabus although it is very rare.
  2. Cut-Off: This is the very important key point among all these. You must be aware of how the cut-off is made. This is not a fix kind of thing. It has been changed in every exam by up UPSC. Mainly the cut-off depends upon the no. of students appeared in exam, difficulty level of the questions & the marks obtained by the candidates in exams. After completion of every exam, UPSC release the cut-off, kindly go thru the UPSC website or visit our CDS cut off page. CDS 1 2018 Written exam cut-off is given below.
S.NoAcademyCut Off
1OTA (Women)69
2OTA (Men)69
  • You can see that the cut-off for OTA is around 35% & for IMA/INA/AFA the cut-off is around is 46%. What does it means? It clearly means that in CDS 1 2018 exam those students who scored minimum 46% able to clear IMA/INA/AFA & similarly those scored 35% minimum able to clear OTA. This clearly indicates that you don’t need to focus on 100% topics & syllabus to clear CDS minimum cut-off. So you can decide a range that how much percentage of syllabus & topic you plan to prepare well to crack CDS written exam.
  • Topics Selection: This is the connecting point of above. Since you have to crack the CDS exam in minimum time frame as exam is at your door. To do a good preparation in minimum time, you need to know the weightage of subjects & topics of all three subjects. For this, get at least 3 to 5 previous years CDS paper analysis. Arrange them in a table & select those which you seem easy & from which most of the questions are asked. Now starts preparing only those topics you have selected.
  • Preparation Level: While most of the students give their 100% effort & dedicated their precious time to prepare themselves for CDS written exam, but they don’t get the results as expected. Why this happen? What’s gone wrong? This may be quite frustrating for many of the students. This situation can be avoided if this point has been taken in consideration before starting the CDS preparation. We must research the standard of the questions of Maths, GK & English, asked in CDS written exam. This can be done by doing a deep analysis of CDS previous year question paper. If you purchase any online or offline study material & test series, kindly take their demo or free version first & verify that those questions are of CDS standard. If you join a coaching institute then take the demo class first & keep your eyes on the standard of questions & teaching.
  • Quality Study Hours: While you are preparing for any competitive exam, there is a huge rush & competition among the candidates. On most of occasion, you ignore this point that for a sure success in any competitive exam, especially like CDS, more than lakhs of students, you can consider that almost all graduate from science, arts, commerce even from IT & computer science apply for CDS, since every one think of getting a defence Jobs. So to become winner among all you need to perform best & for this you need to spend more time on you study. Simply you can calculate that from the 24 hours, how much time you are spending on your quality study. So you need to think on this point & start giving more time & focus on your study. 
  • Practice: This point tells the next key point after quality study hours. You have heard this from most of the students saying that ‘Yaar, Jaanta Tha Fir V Galti Ho Gayi’ (done mistakes besides knowing the answers). Do you know why this happens? Simple! Because lack of practice. You know the proverb ‘Practice makes a man perfect”. Yes, do the more & more practice & this will guarantee you that you will do the best in your exams.

We hope above information will able to help you for the best CDS preparation strategy. We wish you all the best for upcoming CDS written exam & SSB interview.