Seconds & milliseconds
The tool auto-detects whether your timestamp is in seconds (10 digits) or milliseconds (13 digits). You can also force the unit manually.
Unix Timestamp & Time Zone Converter
Convert between Unix timestamps (seconds or milliseconds), human-readable dates, ISO 8601 strings and any time zone. Compare two dates to get the exact difference. Everything runs in your browser — no sign-up, no tracking, no server.
Unix timestamp and time zone converter tool
Private by design. All conversion is done locally with the native Date and Intl APIs. Nothing you type or select is ever uploaded, stored, or logged.
Current Unix time (updates live)
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Input
Digits are auto-detected: 10 digits = seconds, 13 digits = milliseconds.
Uses the IANA time zone database, so daylight saving is applied automatically.
Converted values
Local date
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UTC date
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Selected time zone
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ISO 8601 (UTC)
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ISO 8601 (local offset)
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Unix seconds
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Unix milliseconds
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Relative
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Date to timestamp
Pick a date and time in the selected time zone, then convert it back to a Unix timestamp.
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Date difference
Compare two instants. You can use Unix timestamps in either field, or fill them with the date pickers.
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Quick reference
| Description | Unix seconds | ISO 8601 (UTC) |
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How to use the Unix timestamp converter
- Paste a timestamp. Enter seconds or milliseconds in the input field. The tool auto-detects the unit from the number of digits.
- Pick a time zone. Choose a display time zone from the dropdown. Daylight saving is applied automatically for that zone.
- Read the results. You get local time, UTC, the selected time zone, ISO 8601 in both UTC and local offset, plus a relative description like "3 hours ago".
- Use the live timestamp. The current Unix time updates every second — click it to copy, or click Use seconds as input to fill the input field.
- Reverse the conversion. Use Date to timestamp to turn a date and time back into a Unix timestamp, and Date difference to measure the gap between two instants.
Key features and benefits
Full time zone support
Pick from a curated list of common IANA time zones. Daylight saving transitions are handled by the browser's built-in Intl database.
ISO 8601 output
Get the same instant as an ISO 8601 string in UTC and in local offset form, ready to paste into APIs or config files.
Date differences
Enter two timestamps or pick two dates and see the exact difference in days, hours, minutes and seconds.
Reverse conversion
Turn a date and time in any time zone back into a Unix timestamp with a single click.
Copy anything
Every result row has its own copy button, and a single click copies all values at once.
Privacy and limitations
- Fully client-side. All conversions run in your browser with the native
DateandIntlAPIs. Nothing is sent to a server. - No tracking. The tool does not record which timestamps you convert. There is no analytics on input or output.
- No automatic saving. Values are held in memory only. Reloading the page clears everything.
- Leap seconds are ignored. Unix time is defined as if every day had exactly 86,400 seconds. Leap seconds are not represented, which matches almost every system in practice.
- Year 2038 note. This tool handles 64-bit timestamps, but older 32-bit systems overflow on 19 January 2038 at 03:14:07 UTC. If you are working with legacy code, keep that limit in mind.
- Time zone data. The list of time zones uses the browser's built-in IANA database. Very old browsers may have stale data for regions that changed their rules recently.
Frequently asked questions
What is a Unix timestamp?
A Unix timestamp is the number of seconds that have elapsed since 1 January 1970 at 00:00:00 UTC, not counting leap seconds. It is a compact way to represent a moment in time that does not depend on any time zone.
What is the difference between seconds and milliseconds in a timestamp?
A Unix timestamp in seconds has 10 digits today, while one in milliseconds has 13 digits. JavaScript uses milliseconds internally in
Date objects, while most Unix systems and APIs use seconds. This tool automatically detects which one you have entered based on the number of digits.Does a Unix timestamp change with time zones?
No. A Unix timestamp is always the same instant regardless of where you are. Time zones only affect how that instant is displayed — for example, the same timestamp could be 09:00 in London and 04:00 in New York.
How does this tool handle daylight saving time?
Daylight saving time is handled by the browser's built-in
Intl API, which uses the IANA time zone database. When you select a time zone, the conversion accounts for whether that zone is currently on daylight saving or standard time.What is ISO 8601 format?
ISO 8601 is an international standard for representing dates and times. An example is
2026-10-13T14:30:00Z, where T separates the date and time and Z indicates UTC. ISO 8601 is unambiguous and sortable, which makes it popular in APIs and databases.What is the Year 2038 problem?
Many older systems store Unix timestamps as a signed 32-bit integer, which can only represent times up to 03:14:07 UTC on 19 January 2038. After that moment those systems overflow. Modern systems use 64-bit integers, which will not overflow for billions of years.
A practical guide to Unix timestamps and time zones
Every system that deals with time eventually has to answer the same question: how do you represent a moment so that everyone agrees on what it means? The Unix timestamp is one of the simplest answers. It counts the seconds since 00:00:00 UTC on 1 January 1970 and stores them as a single integer. That integer is the same number everywhere in the world, no matter which time zone you are reading it from.
Why time zones exist at all
If Unix time is unambiguous, why do time zones matter? Because humans do not experience time as a single number. We experience it as a local clock that matches the sun. A meeting scheduled for 09:00 in London is 04:00 in New York and 13:30 in Mumbai. Time zones are the translation layer between the abstract instant and the clock on the wall.
Daylight saving time complicates this further. Zones that observe DST shift by an hour in spring and back in autumn, and the dates of those shifts vary by country and sometimes by year. Never hardcode an offset. Always let a proper time zone database — like the IANA database used by the browser's Intl API — handle the conversion.
Seconds, milliseconds and precision
Unix time is traditionally measured in seconds, which gives about a 68-year range in a signed 32-bit integer. That is the origin of the Year 2038 problem. Modern systems store Unix time in 64-bit integers, which will not overflow for roughly 292 billion years. JavaScript, though, uses milliseconds internally in its Date object, which is why the same instant can be represented as 1760328600 (seconds) or 1760328600000 (milliseconds). The 1000× difference is the single most common source of timestamp bugs, so this tool auto-detects which form you have entered based on the number of digits.
ISO 8601: the interchange format
When you need to send a timestamp to another system, an integer is not always ideal. ISO 8601 is a text format designed to be unambiguous and sortable: 2026-10-13T14:30:00Z. The Z suffix means UTC. If the time is expressed in a local offset instead, the same instant looks like 2026-10-13T16:30:00+02:00. Both forms represent the same moment. This tool shows you both, so you can paste whichever your API expects.
Common pitfalls when working with timestamps
- Assuming local time is UTC. A timestamp is UTC by definition. Confusing the two produces errors that are off by whole hours, often hidden until a user in another region notices.
- Storing timestamps as formatted strings. Strings cannot be compared or sorted efficiently. Store them as integers and format them only at the edges of your application.
- Ignoring leap seconds. Unix time does not include leap seconds. If you need precise astronomy-grade time, Unix time is not the right tool.
- Forgetting DST transitions. Scheduling systems need to know whether a given local time falls inside a DST gap or a DST repeat. Libraries that handle this correctly are worth using.
About this tool
This Unix timestamp converter is part of the TempScript free online tools collection. It runs entirely in your browser, requires no account, and never sends your data anywhere. If you work with APIs and databases regularly, you may also find our JSON formatter and URL encoder and decoder useful for quick formatting tasks.
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