Two countries run on UTC+5:30. That is the entire list.
India and Sri Lanka are the only nations that use the offset as a legal civil standard. No other territory does.
Which countries keep IST?
India operates on India Standard Time, fixed at UTC+5:30 with no seasonal change. Sri Lanka uses Sri Lanka Standard Time, the same offset, maintained under its own authority. The clocks match, but the legal standards are separate.
| Country | Standard time name | Offset | IANA zone |
|---|---|---|---|
| India | India Standard Time (IST) | UTC+5:30 | Asia/Kolkata |
| Sri Lanka | Sri Lanka Standard Time (SLST) | UTC+5:30 | Asia/Colombo |
India runs one clock for 1.35 billion people
India spans roughly 29° of longitude, a solar difference of nearly two hours from east to west. Yet every state, every island territory, and every railway timetable runs on one offset: UTC+5:30. The IANA identifier is Asia/Kolkata. No other Indian zone exists in the database, and no legislative change is pending for 2026 or 2027.
The reference meridian is 82.5°E, passing through Mirzapur near Prayagraj. India adopted it on 1 January 1906, and the Republic kept it after independence. The official timekeeper is CSIR, National Physical Laboratory in New Delhi, operating under the Legal Metrology Act.
India’s population is 1,352,617,328.
Sri Lanka shares the clock, not the law
Sri Lanka Standard Time sits at the same UTC+5:30 offset but is a distinct legal standard. From 1996 to 2006 the country moved to UTC+6:00 as an energy-saving measure, then reverted. Since 2006 the offset has held steady. No daylight saving time is observed.
For a direct comparison, see Sri Lanka time vs India time.
Who used UTC+5:30 in the past?
No current sovereign territory beyond India and Sri Lanka uses the offset. Three places did, and left it behind decades ago.
- Maldives used UTC+5:30 until the 1960s, then switched to UTC+5:00.
- Pakistan (then West Pakistan) used UTC+5:30 before moving to UTC+5:00.
- Bangladesh (then East Pakistan) used UTC+5:30 before adopting UTC+6:00 after independence.
The current arrangement has been stable since Sri Lanka’s reversion in 2006.
Which nearby countries are 15 or 30 minutes off?
Every country bordering India or sitting just beyond its edges uses a different offset. The gap is always 15 or 30 minutes.
| Country | Offset | Difference from IST |
|---|---|---|
| Nepal | UTC+5:45 | +15 min |
| Pakistan | UTC+5:00 | , 30 min |
| Bangladesh | UTC+6:00 | +30 min |
| Bhutan | UTC+6:00 | +30 min |
Nepal’s 45-minute offset puts Kathmandu 15 minutes ahead of New Delhi. Pakistan runs 30 minutes behind. Bangladesh and Bhutan are 30 minutes ahead. None of them share India’s clock.
Why does India use a half-hour offset?
Most countries align to full-hour offsets. Only a handful use a :30 or :45 shift: India (UTC+5:30), Iran (UTC+3:30), Afghanistan (UTC+4:30), Myanmar (UTC+6:30), and Nepal (UTC+5:45).
India’s choice dates to 1906. British India picked the 82.5°E meridian to sit centrally among the subcontinent’s major population centres. The decision was administrative, not astronomical. For the full backstory, see Why is India 30 minutes off?.
No country is scheduled to adopt or drop UTC+5:30 in 2026 or 2027. If your scheduling depends on this offset, the lineup is stable.