Timestamp / Timezone
Convert a Unix timestamp across IANA timezones and ISO-8601 datetimes.
Your timezone
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| Timezone | Date | Time | Offset | Abbr | |
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Tips
- Paste a Unix timestamp, then toggle s / ms or hit Auto-detect (≥13 digits is treated as ms).
- Toggling s/ms preserves the moment — the displayed value is reformatted, the underlying instant is unchanged.
- Day delta (+1d / -1d) shows when a zone is on a different calendar date than UTC.
- Click ISO / s / ms chips to copy that representation.
- Everything runs locally via the browser's built-in Intl tz database.
Timestamps and timezones, made concrete
A Unix timestamp is a single number — the seconds (or milliseconds) since 1970-01-01 UTC. It carries no timezone information by itself; the timezone is something you apply when you want to display the moment as a wall-clock time. This tool takes a timestamp and shows the same instant rendered in every IANA timezone you care about.
Seconds, milliseconds, microseconds
Three resolutions appear in the wild: Unix seconds (10-digit numbers around the year 2026), milliseconds (13-digit, used by JavaScriptDate.now() and most JSON APIs), and microseconds (16-digit, common in databases and tracing systems). When you paste a value, the input is interpreted according to its magnitude.
IANA timezones vs offsets
An offset like +09:00 tells you how far the local clock is from UTC at a single instant. An IANA timezone like Asia/Seoul or America/Los_Angeles describes the full set of rules — including daylight saving transitions, historical changes, and unusual offsets — that govern that region's clock. Always store and exchange timestamps in UTC; only apply a timezone at the moment of display.
Daylight saving, briefly
Many regions shift their clock forward an hour in spring and back in autumn. This creates two edge cases: a moment that does not exist (the clock jumps from 02:00 to 03:00) and a moment that occurs twice (the clock falls back from 03:00 to 02:00). Code that schedules events in local time must handle both. Storing in UTC and converting only at the boundary is the simplest way to avoid the problem.