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Timestamp Converter

Convert between Unix timestamps (seconds/milliseconds) and ISO 8601 / JST / UTC. For log analysis, API debugging, and date verification during data migration.

✅ 100% free, no signup, runs entirely in your browser

Current timestamp
sec:
ms:
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📖 How to Use

  1. 1
    Enter a timestamp or datetime string
    Type a Unix timestamp (seconds or milliseconds) or a datetime string in ISO 8601 / RFC 2822 format. Seconds vs milliseconds are detected automatically by digit count.
  2. 2
    Check the conversion results
    Unix seconds, milliseconds, ISO 8601 (UTC/JST), RFC 2822, day of week, and relative time are all shown together. Click any row to copy that value.
  3. 3
    Adjust with the offset buttons
    Use the -1 day / -1 h / +1 h / +1 day buttons to shift the timestamp and verify boundary values or adjacent log times.

❓ FAQ

How are seconds and milliseconds distinguished?
By digit count: 13+ digits are treated as milliseconds; 10-digit values are treated as seconds.
What is JST?
JST is Japan Standard Time, UTC+9. It is 9 hours ahead of UTC.
What is a Unix timestamp?
The number of seconds elapsed since 1970-01-01 00:00:00 UTC (the Unix epoch). It is the standard numeric date format used in programming and databases.