QUICKTOOLS GUIDE
Understanding Unix Timestamps
Learn what Unix timestamps represent and how seconds differ from milliseconds.
In this guideUnix time is commonly represented as seconds since 1970-01-01 00:00:00 UTC.Many JavaScript APIs use milliseconds instead.Always confirm the unit before converting a timestamp.
The key ideas
- Unix time is commonly represented as seconds since 1970-01-01 00:00:00 UTC.
- Many JavaScript APIs use milliseconds instead.
- Always confirm the unit before converting a timestamp.
How the calculation or process works
1,700,000,000 seconds ≠ 1,700,000,000 milliseconds
If a system gives milliseconds but your tool expects seconds, divide by 1,000 first.
Common mistakes
- Assuming every timestamp is in seconds.
- Ignoring the time zone used when displaying the converted date.
- Changing the original value instead of keeping the raw timestamp for debugging.
Use the related QuickTools utility
Once you understand the method, the QuickTools Unix Timestamps page can handle the repetitive part of the task.
Important: A general guide explains a method; it does not know the rules, assumptions, or requirements of a particular business, contract, institution, or software system. Check those requirements when they matter.