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Half-Hour and Quarter-Hour Time Zones

Why India (UTC+5:30), Nepal (UTC+5:45), and others use non-whole-hour offsets — and how to convert correctly.

Not every country uses a whole-hour UTC offset. India (UTC+5:30), Iran (UTC+3:30 or +4:30 with rules), Nepal (UTC+5:45), and Australian Central Time (UTC+9:30) use 30- or 45-minute differences. Rounding to the nearest hour breaks scheduling.

Major examples

  • UTC+5:30 — India, Sri Lanka (standard time)
  • UTC+5:45 — Nepal (the world's only 45-minute national offset)
  • UTC+9:30 — Australian Central Standard Time
  • UTC+3:30 — Iran standard time (DST rules may apply)
  • UTC+4:30 — Afghanistan
  • UTC+6:30 — Myanmar; UTC+10:30 — Lord Howe Island (Australia)

Why they exist

Zones were shaped by railways, colonial administration, and political choices — not math convenience. India unified on IST (UTC+5:30) nationwide. Nepal chose +5:45 partly to differ from neighboring India and China offsets.

Conversion tips

Avoid mental math with decimals — DST still applies where relevant. Use the Convert with source zone, target zone, and date. Check Countries for live offsets. When scheduling International Meetings with India, confirm IST, not a vague "India time."