Delhi Time Zone: India Standard Time (IST) and UTC+5:30
Delhi, the capital of India, operates on India Standard Time (IST) at UTC+5:30 — five and a half hours ahead of Coordinated Universal Time. The IANA timezone identifier used by computers and phones is Asia/Kolkata, but it applies to the entire country: Delhi, Mumbai, Bangalore, Chennai and every other Indian city keep exactly the same time. A common point of confusion is New Delhi versus Delhi — New Delhi is the formal capital district inside the larger metropolis of Delhi, so "New Delhi time" and "Delhi time" are one and the same.
India's single-timezone policy is a deliberate choice. The country spans nearly 30 degrees of longitude — enough for two conventional time zones — yet it runs on one clock for administrative simplicity and national unity. The reference line is the 82.5°E meridian near Mirzapur, chosen when British India standardised railway time; at 15 degrees per hour, 82.5° works out to exactly 5 hours 30 minutes ahead of Greenwich. Proposals to split India into two zones or shift IST forward resurface from time to time, particularly from the north-east where the sun rises very early, but IST has remained unchanged since Independence.
India does not observe daylight saving time. Delhi stays at UTC+5:30 every day of the year. When your time difference with Delhi changes with the seasons, it is because clocks moved in London, New York or Berlin — never in India. This stability makes Delhi easy to schedule against once you memorise a few anchors: London is 5 hours 30 minutes behind Delhi in winter (GMT) and 4 hours 30 minutes behind in summer (BST); New York is 10 hours 30 minutes behind during EST and 9 hours 30 minutes behind during EDT; Central Europe is 4 hours 30 minutes behind in winter (CET) and 3 hours 30 minutes behind in summer (CEST).
As the seat of India's government, Parliament, Supreme Court and most ministries, Delhi runs on official working hours of roughly 9:00 AM to 5:30 PM IST. For international callers that creates clear windows: a 9:00–11:00 AM meeting in London lands at 2:30–4:30 PM in Delhi (winter), comfortably inside the working day. US East Coast mornings are Delhi evenings — 8:30 AM in New York is 7:00 PM in Delhi during winter — so India–US calls usually settle into an early-morning-US / late-evening-India rhythm. With the Gulf the difference is small: Dubai is just 1 hour 30 minutes behind Delhi, and with Singapore or Hong Kong, Delhi is 2 hours 30 minutes behind.
Delhi sits at about 28.61°N, 77.21°E, west of the IST reference meridian, so solar noon arrives roughly 21 minutes after clock noon. Combined with its northerly latitude, that gives Delhi long summer evenings and short winter days relative to cities in India's south and east — but the clock on the wall always reads the same as everywhere else in the country.