India Standard (IST)
Mumbai operates on India Standard (IST). This time zone does not observe Daylight Saving Time.
Time Zone: India Standard Time (IST) — Standard Offset: UTC+5:30 (IST) — DST: Not observed
Country: India
This city does not observe Daylight Saving Time. The UTC offset remains constant year-round, which simplifies international scheduling.
India Standard Time is UTC+5:30 — one of the world's few half-hour offset time zones. This unusual offset means India is never a round number of hours from any Western country: 5.5 hours ahead of London, 10.5 hours ahead of New York, and 3.5 hours ahead of Dubai. The half-hour difference catches people off guard and is a common source of scheduling errors. India does not observe Daylight Saving Time, keeping the offset constant but making it shift relative to DST-observing countries.
Mumbai is India's financial capital, home to the Bombay Stock Exchange (BSE, Asia's oldest, founded 1875) and the National Stock Exchange (NSE). Trading hours run from 9:15 AM to 3:30 PM IST. Mumbai also houses the Reserve Bank of India and the headquarters of most major Indian banks and financial institutions. For anyone in international finance, IST is a critical time zone — India's $3.7 trillion economy and 1.4 billion consumers make it impossible to ignore.
India's IT outsourcing industry has made IST one of the most important time zones in global technology. Companies like TCS, Infosys, and Wipro employ millions of tech workers who regularly coordinate with US and European clients. Many Indian IT professionals work flexible or shifted hours — starting at 1:00 PM or 2:00 PM IST to maximize overlap with US morning hours (9-10 AM ET = 7:30-8:30 PM IST). This has created a unique '24-hour follow-the-sun' development model.
The US-India scheduling window is narrow but workable. The sweet spot is 8-10 AM ET / 6:30-8:30 PM IST — end of the US morning catches India in the evening. For UK-India coordination, the overlap is better: 9 AM GMT = 2:30 PM IST, giving a full afternoon of overlap. India to Singapore/Hong Kong is manageable at 2.5-3 hours difference. The key rule: always double-check the half-hour offset when scheduling, and specify IST explicitly to avoid confusion.