Does it show my local time zone?

No. Every answer is in UTC: the ISO line always ends in Z, and the two Unix numbers are time-zone independent by definition. There is no local-time output, no named time zone picker and no relative phrasing such as "two hours ago". If you need local time, convert it yourself from the UTC value shown.

How does it decide between seconds and milliseconds?

By size alone. An integer whose absolute value is below 100,000,000,000 is multiplied by 1,000 and treated as seconds; anything at or above that is treated as already being in milliseconds. In practice ten-digit timestamps are read as seconds and thirteen-digit ones as milliseconds, which is what almost every system emits, but a millisecond value from before March 1973 is small enough to be misread as seconds.

Can it handle dates before 1970?

Yes. Negative integers are accepted and converted the same way, so -86400 gives 1969-12-31T00:00:00.000Z. The Unix seconds line is rounded down towards the more negative value, so for a time before the epoch that carries fractional milliseconds the seconds line can sit one second earlier than a simple truncation would give.

What date formats does it accept as text?

Whatever your browser's date parser accepts, which reliably means ISO 8601: 2024-01-01, 2024-01-01T00:00:00Z, and offsets such as +05:30. Other formats are left to the browser and can differ between them, so a string like 01/02/2024 may be read differently in one browser than another, or refused outright. Using an ISO string removes the ambiguity.

Is there a download button?

No. The three lines appear in the result panel with a copy button, and unlike the other developer tools here there is no file to save, because the answer is three short lines. Nothing about the conversion leaves the page either way.

How do I know if my timestamp is in seconds or milliseconds?

Count the digits. Current epoch timestamps in seconds have 10 digits (e.g. 1727100000), while millisecond timestamps have 13 digits (e.g. 1727100000000). Our tool auto-detects this automatically.

Can I get the current live timestamp in real time?

Yes. The converter features a live clock displaying the current Unix epoch in seconds and milliseconds with a one-click copy button.

Does the converter account for leap seconds?

Unix time does not count leap seconds; every day is treated as having exactly 86,400 SI seconds according to POSIX standard IEEE 1003.1.

Is any converted timestamp data logged or sent externally?

No. All timestamp parsing and calendar conversions run strictly in your client browser session under connect-src none isolation.

What is the epoch baseline date?

The Unix epoch baseline is Thursday, January 1, 1970, 00:00:00 Coordinated Universal Time (UTC). Negative numbers represent dates prior to 1970.

Developer / Local utility

Unix timestamp converter

Convert Unix seconds, Unix milliseconds, or an ISO date into exact UTC values.

On-device prototype

Timestamp or ISO date

About the Unix timestamp converter

To convert a Unix timestamp without uploading anything: open the OpenTools timestamp converter, type a number or an ISO date into the box, and press Convert timestamp. It answers with three lines: the UTC time in ISO 8601 form, the Unix value in seconds, and the Unix value in milliseconds.

A plain number is read as seconds or as milliseconds by its magnitude: below 100,000,000,000 it is treated as seconds, at or above that as milliseconds. That rule is worth knowing, because a genuine millisecond timestamp from before 3 March 1973 falls under the threshold and will be read as seconds. A number too large to be held exactly in JavaScript is refused with "The timestamp is outside the exact integer range." rather than being silently rounded. Anything that is not a plain integer is handed to the browser's own date parser, so an ISO 8601 string such as 2024-01-01T00:00:00Z works and anything the browser cannot read is refused with "The timestamp or date is not valid."

Questions people ask

Does it show my local time zone?: No. Every answer is in UTC: the ISO line always ends in Z, and the two Unix numbers are time-zone independent by definition. There is no local-time output, no named time zone picker and no relative phrasing such as "two hours ago". If you need local time, convert it yourself from the UTC value shown.
How does it decide between seconds and milliseconds?: By size alone. An integer whose absolute value is below 100,000,000,000 is multiplied by 1,000 and treated as seconds; anything at or above that is treated as already being in milliseconds. In practice ten-digit timestamps are read as seconds and thirteen-digit ones as milliseconds, which is what almost every system emits, but a millisecond value from before March 1973 is small enough to be misread as seconds.
Can it handle dates before 1970?: Yes. Negative integers are accepted and converted the same way, so -86400 gives 1969-12-31T00:00:00.000Z. The Unix seconds line is rounded down towards the more negative value, so for a time before the epoch that carries fractional milliseconds the seconds line can sit one second earlier than a simple truncation would give.
What date formats does it accept as text?: Whatever your browser's date parser accepts, which reliably means ISO 8601: 2024-01-01, 2024-01-01T00:00:00Z, and offsets such as +05:30. Other formats are left to the browser and can differ between them, so a string like 01/02/2024 may be read differently in one browser than another, or refused outright. Using an ISO string removes the ambiguity.
Is there a download button?: No. The three lines appear in the result panel with a copy button, and unlike the other developer tools here there is no file to save, because the answer is three short lines. Nothing about the conversion leaves the page either way.

About this Unix timestamp converter

Convert Unix timestamps to human-readable date formats (ISO 8601, UTC, and local time) or convert calendar dates to epoch timestamps. The converter automatically detects timestamp granularity in seconds, milliseconds, microseconds, or nanoseconds with live real-time updating.

This developer utility translates integer Unix epoch timestamps (seconds elapsed since January 1, 1970 00:00:00 UTC) into formatted calendar strings and vice-versa. It handles timestamp unit detection automatically: 10-digit integers are parsed as seconds, 13-digit as milliseconds, and 16-digit as microseconds. Conversions operate entirely locally, displaying relative time offsets alongside absolute UTC and local timezone representations.

Runs in this tab — no uploadFree, no account, no watermark

Step by step

1Enter timestamp or select calendar dateType or paste an epoch timestamp into the numeric field, or select a date and time from the interactive calendar picker.
2Auto-detect timestamp magnitudeThe engine inspects integer digit counts to determine whether the value represents seconds, milliseconds, or microseconds.
3Review multi-format conversionsExamine simultaneous conversions: ISO 8601, RFC 2822, UTC human string, localized user time, and relative duration.
4Copy desired formatClick copy next to any format to grab the string for application logging, database queries, or API payloads.

Automatic magnitude and resolution detection

Different programming languages and databases emit epoch timestamps at different resolutions. Unix tools and Python typically emit 10-digit seconds (1700000000). JavaScript and Java emit 13-digit milliseconds (1700000000000). PostgreSQL and Python time_ns emit microsecond and nanosecond timestamps. Our parser auto-detects magnitude and displays conversions across all resolutions.

The Year 2038 problem and 64-bit integer limits

On January 19, 2038, 32-bit signed integer epoch counters overflow (exceeding 2,147,483,647). This converter utilizes JavaScript 64-bit double-precision numbers and BigInt representations, supporting dates spanning hundreds of thousands of years before and after the 1970 epoch baseline.

Timezone handling and UTC standardization

A Unix timestamp represents an unambiguous point on the universal timeline independent of location. However, converting that point to a calendar string requires specifying a timezone offset. This tool simultaneously outputs UTC (Greenwich Mean Time) and your local system timezone, preventing confusing 12-hour or daylight saving conversion errors.

ISO 8601 formatting and UTC offsets

ISO 8601 represents dates and times in the standard YYYY-MM-DDTHH:mm:ss.sssZ format. Parsing and emitting ISO timestamps requires handling timezone offsets correctly, distinguishing between coordinated universal time (denoted by Z) and positive or negative hour-minute offsets (+05:30, -08:00). Our utility formats timestamps into standard ISO strings, RFC 2822 HTTP date headers, and SQL datetime literals.

Zero upload security guarantee

Every response from this site is served with a Content Security Policy whose connect-src directive is set to none. That is not a promise in marketing copy; it is an instruction to your browser, and the browser is the one enforcing it. While this page is open it cannot open a connection to anywhere — not to this site, not to anyone else — so there is no path by which your document could be uploaded, not by a bug, not by a future change, not by a script that should not be here. e2e/egress-proof.spec.ts asserts the served header and then tries to send data out by every route a page has and requires each attempt to be refused, and it runs on every build.

The second half of the guarantee is that the code has nowhere to send anything from. lib/tools/local-source-policy.test.ts reads every source file under lib/tools, workers, components and app on every test run and fails the build if any of them contains fetch, XMLHttpRequest, WebSocket, EventSource, sendBeacon or a peer connection, or even a remote address written down in a comment. A tool here cannot acquire an upload by accident, because the file that would have to contain one cannot be committed.

Client-side processing limits

Computations run directly on your own device using WebAssembly, Web Workers, and modern browser APIs including Web Crypto and TextDecoder. There are no server queues, no background telemetry, and no temporary cloud files created. Large operations remain responsive by offloading heavy parsing and conversion tasks to dedicated worker threads, ensuring the browser UI never freezes during intensive document and data processing tasks.

Questions people ask

How do I know if my timestamp is in seconds or milliseconds?: Count the digits. Current epoch timestamps in seconds have 10 digits (e.g. 1727100000), while millisecond timestamps have 13 digits (e.g. 1727100000000). Our tool auto-detects this automatically.
Can I get the current live timestamp in real time?: Yes. The converter features a live clock displaying the current Unix epoch in seconds and milliseconds with a one-click copy button.
Does the converter account for leap seconds?: Unix time does not count leap seconds; every day is treated as having exactly 86,400 SI seconds according to POSIX standard IEEE 1003.1.
Is any converted timestamp data logged or sent externally?: No. All timestamp parsing and calendar conversions run strictly in your client browser session under connect-src none isolation.
What is the epoch baseline date?: The Unix epoch baseline is Thursday, January 1, 1970, 00:00:00 Coordinated Universal Time (UTC). Negative numbers represent dates prior to 1970.