Unix Timestamps Explained: Seconds, Milliseconds, and Time Zones
Learn timestamp units, UTC, local time display, and common conversion mistakes.
A Unix timestamp represents elapsed time from the Unix epoch. Many systems store seconds, while JavaScript commonly uses milliseconds for Date timestamps.
Check the unit first
A seconds timestamp and a milliseconds timestamp differ by a factor of 1,000. A unit mismatch can produce a date far in the past or future.
Understand time zones
The underlying instant and its displayed local time are different concepts. Reports should state the timezone used.
Validate the result
Compare the converted date against the source system and check daylight-saving behavior where relevant.
Try the related tools
If you are working with important data, preserve the original, test on a sample, and validate the final result before using it in a production workflow.
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QueryCherry offers focused utilities for common data tasks. Basic tools are available without an account.
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