Why Some Zones Differ by 30 or 45 Minutes
Exploring India (UTC+5:30), Nepal (UTC+5:45), South Australia (UTC+9:30), and Chatham Islands (+12:45).
While most time zones are whole-hour offsets from UTC, several major nations choose fractional offsets. India adopted UTC+5:30 in 1906 as a balanced compromise between the eastern longitude of Kolkata and the western longitude of Mumbai.
Nepal established UTC+5:45 based on the meridian passing through the mountain of Gauri Sankar. Australia features Central Standard Time at UTC+9:30 (and UTC+10:30 during daylight saving). The Chatham Islands of New Zealand enforce UTC+12:45. When scheduling with contacts in these regions, meeting planners must support non-integer offset mathematics.
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Test daylight transitions, fractional offsets, and team availability on our interactive instrument.
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