Unix Timestamp Converter: Seconds, ms and µs

The Timestamp panel of the date tool reads an epoch number or a date string and turns it back into every useful reading: Local, UTC/ISO 8601, Unix seconds, Unix milliseconds, Relative, ISO week, DOY · Quarter and Leap · Month days. A second field goes the other way, converting a local date-time into an instant. A live card at the top shows the current Unix seconds, so you can copy "now" without leaving the page.

Updated 2026-10-01Reviewed by CalcX Editorial Team4 sources3 min read

How to use it

Read the live card.Current Unix timestamp shows the running epoch in seconds, with the local date-time and millisecond value underneath.
Paste a value.A plain integer is read by digit count and the unit is printed above the cards (Detected as Unix s/ms/μs); a date string such as 2032-02-29 or Jan 1 2026 is parsed as a calendar reading instead.
Convert the other way.Pick a local date-time under Date → timestamp for the same eight cards, including the leap-year line for the date it lands on.

Worked examples

Captured with the browser in UTC+8 at a fixed clock of 2026-10-07 12:00; the live card read 1791345600 (10/7/2026, 12:00:00).

Input	Detected	Readouts
1800000000	Unix s	ISO 2027-01-15T08:00:00.000Z; Local 1/15/2027, 16:00:00; Relative in 100d; ISO week 2027-W02; DOY · Quarter 15 · Q1; Leap · Month days no · 31
1800000000000	Unix ms	the same ISO instant
1800000000000000	Unix μs	the same ISO instant
99999999999	Unix s	5138-11-16T09:46:39.000Z
999999999990	Unix ms	2001-09-09T01:46:39.990Z
−100	Unix s	1969-12-31T23:58:20.000Z; Local 1/1/1970, 07:58:20
Date → 2032-02-29 00:00	—	Local 2/29/2032, 00:00:00; ISO 2032-02-28T16:00:00.000Z; Unix (s) 1961596800; Leap · Month days yes · 29

The unit is chosen by digit count, not by magnitude, and the boundary sits between eleven and twelve digits: 99999999999 (eleven digits) is seconds and lands in the year 5138, while 999999999990 (twelve digits) is milliseconds and lands in 2001 — the same run of nines, 3,137 years apart. A negative integer is allowed and reads as a pre-epoch time, so −100 is 23:58:20 UTC on 31 December 1969. Between twelve and fifteen digits the parser reads milliseconds, and sixteen or more reads microseconds.

Limits

Parsing rules.: Under twelve digits is seconds, twelve to fifteen is milliseconds, sixteen and up is microseconds; text input is handed to the browser's date parser, so stick to ISO-style strings and English month names that parse reliably.
The Local card has no zone picker.: It always shows this browser's zone, so a value that is midnight UTC elsewhere can display a day earlier or later here; read the ISO card when a local date is quoted.
What it does not do.: It reads one instant at a time and does not convert between zones or measure durations. Use World Clock for zone tables and Countdown & Age for time remaining.

Where it helps

Debugging logs and APIs

An API returns 1800000000; the cards confirm the unit, the ISO instant and the local time in one paste, which is usually enough to line an event up with a log window.

Turning a deadline into an epoch

For a scheduler or database field, enter the deadline as a local date-time and copy Unix (s) from the cards — for 2032-02-29 at midnight in UTC+8 that is 1961596800.

References

Wikipedia, Unix time （访问日期：2026-10-01）— the epoch, and seconds versus milliseconds.
Ecma International, ECMAScript Language Specification: Date Time String Format （访问日期：2026-10-01）— the string formats the browser parser accepts.
MDN Web Docs, Date （访问日期：2026-10-01）— local versus UTC fields and out-of-range instants.
ISO, ISO 8601-1:2019, Date and time — Representations for information interchange, iso.org （访问日期：2026-10-01）— the ISO 8601 reading on every card.