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Date & Time • Nov 30, 2025 • 6 min read

Timezone Conversion Without Losing Your Mind

IANA timezone database is the source of truth. Three-letter abbreviations like EST and IST are ambiguous and unsafe.

There are 38 timezone offsets in current use, ranging from UTC-12 to UTC+14. The IANA timezone database (tzdata) is the canonical source — names like "America/New_York" or "Asia/Tokyo" are unambiguous. Three-letter abbreviations like "EST" are NOT — "IST" means Indian Standard Time (UTC+5:30) or Irish Standard Time (UTC+1) or Israel Standard Time (UTC+3). Daylight Saving Time (DST) shifts most US/EU zones by an hour twice a year, on different weekends. Store timestamps in UTC, convert to local zone only at display time. Our Timezone Converter handles common pairs.