Unix Timestamp Converter
Convert epoch numbers and dates, with the unit worked out for you.
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About the Timestamp Converter
Convert between epoch numbers and readable dates in both directions, accepting epoch values in seconds, milliseconds, microseconds or nanoseconds as well as ISO 8601 strings, HTTP dates and the word now. The part that does the real work is unit detection: 1700000000 and 1700000000000 are the same instant written in different units, and passing either to a date function without first deciding which gives you 1970 or 2023 with no warning at all — which is why a pasted timestamp so often appears not to work. Magnitude decides, the guess is stated, and a selector overrides it. Results show UTC and local side by side with the real offset for that date, plus the day of week, ISO week number and day of year.
Why is unit detection necessary?
Because 1700000000 and 1700000000000 are the same instant in different units, and handing either to a date function without deciding gives you 1970 or 2023 with no warning. Magnitude is the only available signal: around 1e9 is seconds, 1e12 is milliseconds, and so on. It is also why a pasted timestamp so often "does not work" in other tools.
Can the detection be wrong?
Yes, for small numbers. A value below about 1e8 is read as seconds, which puts it in the early 1970s — correct if that is what you meant, wrong if it was actually a duration. The unit selector overrides the guess.
What is epoch time?
The number of seconds since 1 January 1970 at 00:00 UTC, not counting leap seconds. It is a single number with no timezone, which is exactly why it is used for machine-readable timestamps.
Why does the local time differ from what I expect?
Local rendering uses your device's timezone and its daylight-saving rules for that specific date — not for today. A timestamp from July may show a different offset from one in January.
Does it handle dates before 1970?
Yes. A negative epoch value is a date before the epoch, and it converts normally.
Is anything sent to a server?
No. All conversion is arithmetic and date formatting in your browser.
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Keywords: unix timestamp converter, epoch converter, epoch to date, milliseconds to date, iso 8601 converter, unix time