Selection data:

According to data from LBSNAA (Lal Bahadur Shastri National Academy of Administration) and analyses published by The Print and PRS Legislative Research:

• CSE 2022: Approximately 13,000 candidates who qualified Mains used English medium vs approximately 500 in Hindi
• The ratio has been roughly 20:1 (English:Hindi) among those who clear Prelims and appear for Mains
• However, this reflects candidate choice, not examiner preference

Key factors in favour of English:

• Vastly more study material, test series, and coaching in English
• Current affairs resources (The Hindu, Indian Express, PIB) are primarily in English
• Technical vocabulary in Economy, International Relations, S&T is English-dominant

Key factors in favour of Hindi:

• Hindi-medium candidates from rural/semi-urban backgrounds may express better in Hindi
• UPSC has no official policy favouring English — examiners are instructed to evaluate content
• Drishti IAS provides comprehensive Hindi-medium materials
• Several Hindi-medium toppers have cleared the exam, including candidates in top 100

Practical recommendation:

• Choose the language in which you think and express best
• Write practice answers in both for 2–3 months; the one where your expression is richer is your medium
• Do not switch mediums between attempts — you lose hard-won fluency

What UPSC explicitly states: 'The medium of answers shall be the candidate's choice... examiners shall be instructed not to penalise on the basis of medium.' — UPSC CSE Rules