Auto-detect as a starting point
Auto-detect uses the numeric magnitude to distinguish typical second and millisecond values. Choose the unit explicitly when the source documentation provides it.
Free online developer utility · no registration or login
Free Unix Timestamp Converter Online
Convert Unix timestamps in seconds or milliseconds to UTC, local time, or ISO 8601. Convert dates back to timestamps online with no registration or login.
- Seconds and milliseconds
- UTC, local, and ISO 8601
- Convert in both directions
- Free online, no registration or login
Timestamp workspace
Convert an instant in either direction
This free online converter handles seconds and milliseconds in your browser. No registration or login is required.
Conversion direction
Auto-detect treats typical 13-digit values as milliseconds. Select the source unit when you know it.
Converted result
Example timestamp · auto-detected seconds
- Unix seconds
- 1704067200
- Unix milliseconds
- 1704067200000
- ISO 8601 (UTC)
- 2024-01-01T00:00:00.000Z
- UTC
- Mon, 01 Jan 2024 00:00:00 GMT
- Local
- Resolving browser timezone…
Convert a Unix timestamp in three steps
A short path from a numeric timestamp or calendar date to the exact representation your next system needs.
- Step 1
Choose a direction
Select Timestamp to date or Date to timestamp to match the value you already have.
- Step 2
Set the unit or interpretation
Choose auto-detect, seconds, or milliseconds for a timestamp—or choose browser local time or UTC for a calendar date.
- Step 3
Review and copy a result
Compare Unix seconds, milliseconds, ISO 8601, UTC, and local time, then copy the exact row you need.
Seconds or milliseconds?
A unit mismatch changes the value by a factor of 1,000, so the converter keeps the choice visible and reports what it used.
Watch for an implausible year
If a modern event lands near 1970 or far into the future, seconds may have been read as milliseconds—or milliseconds as seconds. Switch the unit and convert again.
Negative values are valid
Numbers below zero represent instants before the Unix epoch. They work here when the converted value remains inside the browser Date range.
UTC, local time, and ISO 8601
The timestamp identifies one instant. Timezone and string format only change how that instant is displayed or entered.
One instant, several displays
Unix seconds, Unix milliseconds, ISO 8601 UTC, readable UTC, and local time can all describe the same moment without changing the underlying instant.
Local means this browser
The local result and Local time date input use the timezone resolved by your browser. The workspace shows that timezone beside the interpretation control.
ISO output is UTC
The ISO 8601 row ends in Z, which denotes UTC. Local calendar times around daylight-saving transitions can be skipped or repeated according to browser rules.
Where Unix timestamps appear
Numeric timestamps are compact and language-neutral, which makes them common across application boundaries.
APIs and webhooks
Convert created, updated, scheduled, or delivered fields into ISO or local time while debugging an API response or webhook event.
Logs and databases
Translate numeric event times before comparing records, tracing a failure, or preparing a date value for a database query.
Token time claims
JWT fields such as iat, nbf, and exp commonly use epoch seconds. Use the related JWT Decoder to inspect the token structure; decoding does not verify its signature.
What the converter supports—and does not
The page stays focused on exact, single-value conversions that the browser Date model can represent honestly.
Millisecond precision
The converter supports seconds and milliseconds. It does not claim exact microsecond or nanosecond conversion because browser Date values store milliseconds.
One value at a time
Batch lists and natural-language dates are outside this page's scope. Enter one numeric timestamp or one calendar date for a clear result.
Browser date boundaries
Out-of-range numeric values are rejected. Local calendar input also follows the timezone and daylight-saving behavior configured in the browser.
Privacy and limits
Conversion runs in this browser tab. Check the source unit and timezone interpretation before using a result in production data.
- Auto-detect uses numeric magnitude as a convenience; select seconds or milliseconds explicitly when the source format is known.
- Browser local time uses the timezone and daylight-saving rules configured in this browser.
- The converter supports seconds and milliseconds, not exact microsecond or nanosecond precision.
- Values outside the JavaScript Date range are rejected, and the page converts one value at a time.
Unix Timestamp Converter FAQ
Straight answers about epoch time, seconds, milliseconds, UTC, local time, browser processing, and this converter's precision.
Is this Unix timestamp converter free to use?
Yes. This is a free online Unix timestamp converter. You can convert timestamps and dates without registering, creating an account, or logging in.
What is a Unix timestamp?
A Unix timestamp is a number that represents elapsed time from 1970-01-01 00:00:00 UTC. Systems commonly store it in whole seconds or milliseconds.
Is Unix time the same as epoch time?
In common developer usage, yes: Unix time and epoch time usually mean elapsed seconds from the Unix epoch at 1970-01-01 00:00:00 UTC. Other systems can define a different epoch, so check the source when the value comes from a specialist format.
How do I tell seconds from milliseconds?
Current timestamps in seconds are typically about 10 digits, while milliseconds are typically about 13 digits. Auto-detect uses the value's magnitude and reports its choice; select a unit explicitly when you know the source format.
Does a Unix timestamp contain a timezone?
No. A Unix timestamp identifies an instant independent of timezone. UTC and local time are different displays of that same instant, not different timestamp values.
Can I convert a date back to a Unix timestamp?
Yes. Choose Date to timestamp, enter a calendar date and time, then specify whether the input should be interpreted as browser local time or UTC. The result includes both seconds and milliseconds.
What does a negative Unix timestamp mean?
A negative Unix timestamp represents an instant before 1970-01-01 00:00:00 UTC. This tool accepts negative values when the resulting date is within the browser's supported range.
Why do UTC and local time look different?
They apply different timezone offsets to the same instant. The local result uses the timezone configured in your browser, while the ISO and UTC results use UTC.
Does the input leave my browser?
No. The conversion runs in this browser tab, and the page does not upload the entered timestamp, calendar date, or generated result. No registration or login is required.
Does this tool support microseconds or nanoseconds?
No. This page converts seconds and milliseconds only. JavaScript Date values use millisecond precision, so treating microsecond or nanosecond input as exact would be misleading.
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