Why does India use a half-hour time zone?

India adopted UTC+5:30 as a single national time zone to split the difference between the country’s eastern and western extremes. The offset represents a compromise: far-eastern India would naturally be closer to UTC+6, while the west would suit UTC+5. A single half-hour offset keeps the entire country on one clock.

Which country has a quarter-hour time zone?

Nepal uses UTC+5:45, the most well-known quarter-hour offset. New Zealand’s Chatham Islands use UTC+12:45 (UTC+13:45 during DST). The French Polynesian Marquesas Islands use UTC-9:30, another non-standard fractional offset.

Do fractional time zones cause software bugs?

They can. Software that assumes time zone offsets are always whole hours will miscalculate times in India, Nepal, Iran, and other fractional zones. Using a robust time library that supports the full IANA database avoids these issues.

Half-Hour and Quarter-Hour Time Zones

June 11, 2026

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Frequently Asked Questions

Why does India use a half-hour time zone?: India adopted UTC+5:30 as a single national time zone to split the difference between the country’s eastern and western extremes. The offset represents a compromise: far-eastern India would naturally be closer to UTC+6, while the west would suit UTC+5. A single half-hour offset keeps the entire country on one clock.
Which country has a quarter-hour time zone?: Nepal uses UTC+5:45, the most well-known quarter-hour offset. New Zealand’s Chatham Islands use UTC+12:45 (UTC+13:45 during DST). The French Polynesian Marquesas Islands use UTC-9:30, another non-standard fractional offset.
Do fractional time zones cause software bugs?: They can. Software that assumes time zone offsets are always whole hours will miscalculate times in India, Nepal, Iran, and other fractional zones. Using a robust time library that supports the full IANA database avoids these issues.