CDS Preparation Guide 2025
Combined Defence Services — Army, Navy, Air Force (for Graduates)
Graduates aged 19–25 (Army), 19–22 (Navy/Air Force) seeking commissioned officer entry into the armed forces. Also open to final-year graduation students.
Exam at a Glance
Conducted By
Union Public Service Commission (UPSC)
Vacancies
450–500 (IMA: ~100, INA: ~45, AFA: ~35, OTA: ~225)
Age Limit
IMA/OTA: 19–25 years; INA: 19–22 years; AFA: 19–23 years
Eligibility
Graduation any discipline (IMA/OTA); Engineering (Navy); Any Graduate (AFA ground duty)
Frequency
Twice per year (CDS I: February; CDS II: September)
Gender Eligibility
Male and female (OTA for females); male only for IMA/INA/AFA flying branch
Applicants/Cycle
4–5 lakh per cycle
Selection Process
- English: 100 questions, 100 marks
- General Knowledge: 100 questions, 100 marks
- Elementary Mathematics: 100 questions, 100 marks (not for OTA)
Pass Rate
Top ~7,000–10,000 called for SSB from 4+ lakh applicants
Key Strategy
CDS written is generally easier than NDA — English and GK alone (OTA track) are very achievable. For IMA/Navy/AFA, the Mathematics paper is Class 10 level only (unlike NDA's Class 12 Math). Time management, not difficulty, is the main challenge.
- Screening: OIR + PPDT (Day 1)
- Psychology: TAT + WAT + SRT + Self Description (Day 2)
- GTO: Group tasks, outdoor leadership exercises (Days 3–4)
- Personal Interview (embedded in Days 3–5)
- Conference (Day 5): Final board decision
Pass Rate
~12–15% of those who appear (CDS SSB tends to be slightly higher than NDA due to graduate maturity)
Key Strategy
Graduates have a natural advantage in CDS SSB — life experience, communication skills, and decision-making maturity are more developed. The challenge is shedding academic persona and showing initiative and leadership instincts.
- Physical measurements
- Vision test
- Hearing and ENT
- Systemic health
- Fitness test
Pass Rate
10–15% rejection at medical post-SSB recommendation
Key Strategy
Check vision and physical standards before applying for each arm. OTA is generally the least restrictive on physical requirements. IMA, Navy, and AFA have stricter vision and physical benchmarks.
Written Exam Papers
English
English Language & Comprehension
General Knowledge
History, Geography, Polity, Science, Current Affairs
Elementary Mathematics (IMA/Navy/AFA only)
Mathematics up to Class 10
Subject-Wise Strategy
General Knowledge
33% of written marks
- Indian History: 1857–1947 independence and post-independence milestones
- Indian Polity: Fundamental Rights, DPSP, Parliament structure
- Defence-related current affairs: exercise names, new weapon systems
- Science: everyday phenomena, basic physics and chemistry
Avoid: Studying only current affairs without static GK — static questions outnumber current affairs in most CDS papers
English
33% of written marks
- Error spotting (tense, subject-verb agreement, preposition)
- Sentence arrangement (ordered paragraphs)
- Reading Comprehension: factual inference
- One-word substitution and idioms
Avoid: Assuming English is easy and not preparing — it is 33% of written marks and the most time-consistent section; under-preparation costs easy marks
Elementary Mathematics (IMA/Navy/AFA)
33% of written marks
- Percentages and profit/loss (5–8 questions always)
- Geometry: Circle theorems, triangle properties
- Trigonometry: Basic identities and simple height/distance
- Mensuration: Area, volume of standard shapes
Avoid: Treating this like NDA Math (it is not) — CDS Math is Class 10 level; 90%+ accuracy is achievable with 4–6 weeks of focused practice
Physical & Medical Standards
Height
MandatoryIMA: 157.5 cm; OTA: 157.5 cm; Navy: 157 cm; AFA: 162.5 cm
Tip: AFA has the highest height requirement; OTA and IMA are the same minimum.
Vision
MandatoryIMA/OTA: 6/6 corrected; AFA Pilot: 6/6 uncorrected; Navy Executive: 6/6
Tip: AFA flying is the most vision-restrictive. CDS OTA allows glasses correction.
Physical Fitness
Qualifying2.4 km run in under 15 minutes; basic strength tests
Tip: Train to sub-12 min 2.4 km for comfort. SSB GTO includes obstacle courses; physical readiness affects confidence and performance in group tasks.
GTO Outdoor Tasks
ScoredIndividual and group obstacle courses, group discussion, lecturette
Tip: Lecturette (3-minute solo speech on a card topic) is unique to CDS SSB — practise public speaking on defence, economy, and social themes.
Service Branches & Career Path
Indian Military Academy (IMA) — Army
Infantry, armoured corps, artillery, signals, engineers
Training
IMA Dehradun — 18 months
Commissioned as
Lieutenant → Captain → Major → Colonel
Growth Path
Same as NDA Army; commissioned at 25 vs NDA's 21–22; slightly slower initial progression
Officers Training Academy (OTA) — Short Service Commission
Army across all arms and services on Short Service Commission
Training
OTA Chennai — 11 months; OTA Gaya for women
Commissioned as
Lieutenant on Short Service Commission (10 years, extendable to 14)
Growth Path
SSC → Permanent Commission (selective, competitive) or civil career post service
Indian Naval Academy (INA) — Navy
Warship operations, submarine, aviation, technical
Training
INA Ezhimala — varies by branch
Commissioned as
Sub Lieutenant
Growth Path
Same career ladder as NDA Navy officers
Air Force Academy (AFA) — Air Force
Flying (pilot) or ground duty (technical, administration)
Training
AFA Dundigal, Hyderabad
Commissioned as
Flying Officer
Growth Path
Flying branch career; ground duty for non-pilot streams
Preparation Timeline
GK and English foundation; Math revision for IMA track
- Complete NCERT History (Class 8–12 modern India chapters)
- Complete NCERT Geography (Class 9–11 relevant chapters)
- English: Grammar book cover-to-cover
- Begin current affairs reading: The Hindu + monthly capsules
Previous papers + timed section practice
- Solve last 8 years CDS GK papers — identify repeating topics
- English: section-level accuracy above 80%
- Math (if IMA): complete all arithmetic and algebra chapters
- Physical: 2.4 km running under 13 minutes
Full paper mocks + SSB conceptual understanding
- 6+ full CDS mocks (all 3 papers if IMA)
- Target: English 75+, GK 65+, Math 70+ (IMA cutoff range)
- Read SSB preparation book (Arihant or Naval SSB guide)
- Begin writing practice for WAT/SRT (Word Association Test, Situation Reaction Test)
OLQ development, mock SSBs, physical readiness
- Mock PPDT with group (video or in-person with peers)
- TAT story writing: 15 stories minimum
- GTO obstacle course: practise in any open grounds
- Personal Interview: prepare life narrative, motivation, current affairs
Career Benefits
Commissioned officer status with ₹56,100 basic pay + ₹15,500 MSP = ₹71,600+ basic (total CTC ₹12–15 lakh/year)
OTA Short Service Commission: 10+4 years service, then competitive Permanent Commission conversion or honourable exit with pension after 15 years
Government accommodation, free medical care, subsidised education for children
Women eligible for OTA (Short Service Commission) and select INA/AFA roles
CDS career spans across the same progression as NDA officers — the starting point differs, not the ceiling
Ex-servicemen have priority in state and central government jobs post-retirement
Common Mistakes to Avoid
Applying for IMA when OTA eligibility matches better — OTA has more vacancies and is the only option for women graduates
Underestimating written exam cutoffs: CDS written is easier than NDA but cutoffs are also high; 50–60% total marks is typically needed to qualify
Not preparing for SSB at all: many graduates assume communication skills alone will carry them — SSB evaluates Officer-Like Qualities systematically, not just confidence
Ignoring the lecturette in SSB prep: CDS SSB includes a 3-minute solo lecturette on a card topic; most candidates do not practise this and freeze
Applying only once: age window for IMA (19–25) and OTA (19–25) allows 10 written exam attempts — persistence matters more than any single result
Not using OTA as a stepping stone: OTA SSC + Permanent Commission conversion is a proven path to a long military career; do not dismiss it as "less than IMA"
Frequently Asked Questions
What is the difference between CDS OTA and IMA?
IMA (Indian Military Academy) grants Permanent Commission from the start — a full 35+ year army career. OTA (Officers Training Academy) grants Short Service Commission for 10 years (extendable to 14). OTA officers can apply for Permanent Commission (selective process). Women graduates can only apply for OTA among the CDS tracks.
Is CDS harder than NDA?
The written exam is generally easier — NDA Mathematics is Class 12 level while CDS Math is Class 10 only, and CDS GK is less technical. However, the overall competition is similar in intensity because CDS applicants are graduates with more focused preparation. SSB selection rates are similar.
Can engineering graduates apply for CDS?
Yes. Engineering graduates are eligible for all CDS tracks — IMA, OTA, INA, and AFA. Technical graduate entry (TGC) into the Army is a separate route without written exam; similarly, AFCAT (Air Force) is an alternative to CDS for AFA. Engineering graduates should evaluate all three options.
What salary does a CDS officer receive after training?
After commissioning from IMA/OTA/INA/AFA: Basic Pay ₹56,100 + Military Service Pay ₹15,500 + DA + HRA + Transport Allowance + Kit Maintenance. Total in-hand in a normal posting is approximately ₹80,000–₹1,05,000/month depending on posting location and allowances.
Can I apply for both NDA and CDS?
Not simultaneously — NDA is for Class 12 students (age limit 19.5 years) while CDS requires graduation. However, if you are 19 and have completed graduation, you may overlap with the NDA age limit; check the specific notification. Most candidates naturally transition from NDA (failed age-out) to CDS (graduate entry).
Other Defence & Government Exam Guides
Prepare for CDS Preparation with a mentor who has cleared SSB
Written exam strategy, SSB mock practice, and physical fitness planning from someone who has been through the selection — the most direct path to understanding what the board actually looks for.