Is a timestamp in seconds or milliseconds?

Both exist. Classical Unix time is in seconds. JavaScript, Java and many modern APIs use milliseconds. A 10-digit number is seconds, a 13-digit number is milliseconds. This tool auto-detects based on digit count.

Does the timestamp account for time zones?

The timestamp itself is always UTC. The human-readable date on screen depends on which time zone you display it in. This tool shows both your local time and UTC side by side.

ISO 8601 is the international standard for writing dates and times as text. The classic form is YYYY-MM-DDTHH:MM:SSZ. It is the preferred format for logs, APIs and databases because it sorts alphabetically in the correct order.

Can I convert a date to a timestamp?

Yes. Use the second tab, pick a date and time, and the tool returns the Unix timestamp in both seconds and milliseconds.

Unix Timestamp Converter: Epoch to Date and Back (Free)

What is Unix Time

Unix time is the number of seconds that have passed since midnight on 1 January 1970 Coordinated Universal Time. This moment is called the epoch. Every modern operating system, database, programming language and network protocol represents time this way under the hood because an integer is trivial to store, trivial to compare and does not depend on any local calendar. When you see 1762800000 in a log file or an API response, that is a point in time roughly in November 2026.

Seconds vs Milliseconds

Classical Unix time counts seconds. JavaScript, Java and most web APIs count milliseconds instead because sub-second precision matters for events. A rough rule: if the number is 10 digits long it is seconds, 13 digits is milliseconds, 16 digits is microseconds and 19 digits is nanoseconds. This converter detects the unit from the digit count so you do not have to divide or multiply by hand.

How to Use This Tool

Paste a timestamp in the first tab. The converter figures out the unit and shows the date in multiple formats.
Press Use current time to fill the current Unix time in seconds, handy for comparing to API values.
Switch to the second tab to go the other direction: pick a date and time and get the matching epoch value.
The live Unix time ticker in the header updates every second.

The Year 2038 Problem

Older systems store Unix time in a signed 32 bit integer. The largest value fits roughly 2.1 billion, which translates to 03:14:07 UTC on 19 January 2038. One second later the counter overflows and wraps to a negative number, which most code interprets as December 1901. Embedded devices, legacy servers and old file systems still exposed to this limit are being quietly audited across the industry. New code should use 64 bit integers which push the overflow date 292 billion years into the future. More than enough.

ISO 8601

The ISO 8601 standard is the preferred way to write dates as text. The form 2026-11-11T14:30:00Z is unambiguous, sorts alphabetically in chronological order and is parsed by every major language without extra configuration. If you are logging events or designing an API, prefer ISO 8601 in UTC over human readable strings in the local time zone.

Privacy

All parsing happens in the browser. Nothing is uploaded. The tool works offline after the first load.

Frequently Asked Questions

What is a Unix timestamp?

Seconds since the 1 January 1970 UTC epoch.

Seconds or milliseconds?

10 digits are seconds, 13 are milliseconds. Auto-detected here.

What is the Year 2038 problem?

Signed 32 bit timestamps overflow on 19 January 2038. 64 bit storage avoids it.

Do timestamps have a time zone?

No. The number is always UTC. Only the display changes by time zone.

What is ISO 8601?

The international text format YYYY-MM-DDTHH:MM:SSZ, preferred for logs and APIs.

Can I convert a date back to an epoch?

Yes, with the second tab.

Does this work offline?

Yes, once the page has loaded.