What this Unix timestamp converter does
A Unix timestamp — also called epoch time or POSIX time — is just a count of seconds since 1 January 1970 UTC. It's how computers store nearly every date behind the scenes, and it's completely unreadable to a human. This tool converts one to the other in both directions: type a timestamp and get the date, or pick a date and get the timestamp. Both fields stay in sync live, in seconds or milliseconds, in UTC or your local time zone.
It's built for the moments a raw epoch number shows up somewhere unhelpful — a log line, an API response, a database column, a JSON Web Token's exp or iat claim. Paste it in and read the date; or work the other way and generate a timestamp to test with.
How to use it
Enter one value; the other, plus the extra details, update as you type.
- Enter a Unix timestamp.Type or paste the epoch value in seconds or milliseconds, and pick the matching unit from the dropdown. The "Use now" button fills in the current time.
- Or enter a date & time.Pick a date and time instead, in local time or UTC — the timestamp field updates automatically.
- Check the extra details.The ISO 8601 string, day of week, the alternate unit, and how long ago (or from now) that moment is all appear alongside the main result.
- Copy, print, or download.Grab the result for a bug report, a log entry, or a spreadsheet row.
How the conversion works
Unix time counts seconds forward from a single fixed instant, the epoch: 00:00:00 UTC on 1 January 1970. To turn a timestamp into a date, the count is split into whole days (giving the calendar date via the Gregorian calendar, including leap years) and a remainder of seconds within that day (giving the time). Converting a date to a timestamp is the reverse — count the days since 1970, turn that into seconds, and add the seconds elapsed since midnight.
19,675 days after 1 Jan 1970 → 14 Nov 2023
80,000 seconds = 22h 13m 20s
Result:
2023-11-14T22:13:20Z
Seconds vs. milliseconds
A 10-digit timestamp (like 1700000000) is in seconds; a 13-digit one (like 1700000000000) is in milliseconds, which is what JavaScript's Date.now() and many web APIs return. This tool converts either directly — switch the unit dropdown rather than adding or removing zeros by hand. For an isolated millisecond duration (not a point in time), the milliseconds to time converter is the more direct tool.
UTC vs. local time
A timestamp itself has no time zone — it's the same number everywhere on Earth at that instant. The UTC / Local toggle only changes how that instant is displayed. If you need to see the same moment in a specific zone other than your own, the UTC converter handles that conversion directly.
Quick examples
A few round and notable timestamps, verified against UTC.
| Timestamp | Unit | UTC date & time | Day |
|---|---|---|---|
| 0 | seconds | 1970-01-01 00:00:00 | Thursday |
| 1000000000 | seconds | 2001-09-09 01:46:40 | Sunday |
| 1234567890 | seconds | 2009-02-13 23:31:30 | Friday |
| 1700000000 | seconds | 2023-11-14 22:13:20 | Tuesday |
| 2147483647 | seconds | 2038-01-19 03:14:07 | Tuesday |
That last row is the Year 2038 problem — the moment a signed 32-bit second counter overflows. Working from a date instead and want the ISO string directly? The ISO 8601 converter goes straight between an ISO string and a timestamp.
Who uses it, and for what
- Developers & QA decoding a timestamp field in an API response, log line, or bug report — or generating one to feed into a test case.
- Backend & database engineers checking what a stored epoch column, cache key, or index value actually represents.
- Anyone debugging a token or cookie — the
expandiatclaims in a JWT are almost always Unix timestamps in seconds. - Curious readers working out what a memorable "round" epoch number, like 2,000,000,000, actually falls on.
Just need to know how long ago a moment was, in plain words rather than a timestamp? The time ago calculator gives that phrasing directly. Browsing for the rest of the developer set — cron expressions, an alternate epoch view, or a plain milliseconds-to-time step — starts at the developer tools hub.
Frequently asked questions
What is a Unix timestamp?
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. It is a single integer that represents one specific moment regardless of time zone.
How do I convert a Unix timestamp to a readable date?
Enter the number in the timestamp field above. The date and time field, ISO 8601 string, and day of week update automatically, in either UTC or your local time zone.
Why do some timestamps have 13 digits instead of 10?
A 13-digit value is in milliseconds rather than seconds — JavaScript's Date.now() and many web APIs use milliseconds. Switch the unit dropdown to Milliseconds to convert those directly.
Does the converter account for time zones?
A Unix timestamp itself has no time zone; it counts seconds from a single global instant. What changes is how that instant is displayed — choose UTC to see Coordinated Universal Time, or Local time to see your device's time zone.
What is the Year 2038 problem?
Some older systems store Unix time as a signed 32-bit integer, which overflows at 2,147,483,647 seconds — 03:14:07 UTC on 19 January 2038. Modern 64-bit systems aren't affected, but the limit still shows up in legacy software and file formats.
Can a Unix timestamp be negative?
Yes. Negative values represent moments before 1 January 1970, and this tool accepts and correctly converts them.
Is this tool free and private?
It is completely free with no sign-up. The conversion runs entirely in your browser — your timestamps and dates are never uploaded or stored on a server.
Accuracy & sources
This converter works directly from the definition of Unix time: a running count of seconds (or milliseconds) since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. Every value is produced with standard date-time arithmetic — the same approach any programming language's date library uses — and every example on this page, including the Year 2038 boundary, has been independently verified by hand.
The ISO 8601 string shown with each result follows ISO 8601, the international standard for representing dates and times unambiguously. Written and reviewed by Fletcher Langley, and re-checked whenever the tool changes — last reviewed August 2026.
About the author
Operations and workforce-systems specialist with 14+ years inside shift-based industries and payroll platforms, and a BS in Industrial Engineering. Fletcher writes and reviews the calculators, converters, and guides here — from overnight-shift math to decimal payroll hours — drawing on years spent translating between 12-hour, 24-hour, and machine-readable time formats.
Written & reviewed by Fletcher Langley · Last updated: August 2026