Unix Timestamp Converter — Epoch ↔ Date, Auto Sec/Millis, UTC & Any Timezone

This free Unix timestamp (epoch) converter lets you convert any Unix timestamp to a human-readable date and any date back to an epoch — instantly, in both directions. Paste a 10-digit (seconds) or 13-digit (milliseconds) timestamp and the unit is auto-detected. The same moment is shown in UTC, your local timezone, and any IANA timezone you choose, with ISO 8601, RFC 2822 and relative time all displayed at once. A live current epoch counter keeps ticking, and every value can be copied with one click. No installation, no upload — everything runs in your browser.

How to use

1. Paste a Unix timestamp (e.g. 1700000000) into the epoch field — the unit (seconds or milliseconds) is auto-detected and the date is shown immediately.
2. Or enter a date/time in ISO 8601 format (e.g. 2023-11-14T22:13:20Z) into the date field to get the epoch back.
3. Choose a timezone from the dropdown to see the same moment in UTC, local time, and a third timezone of your choice.
4. Click 'Copy' next to any value to copy it to your clipboard.
5. Click 'Use now' to load the current epoch into the input and convert it instantly.

What is a Unix timestamp (epoch)?

A Unix timestamp (also called epoch time or POSIX time) is the number of seconds elapsed since 1970-01-01T00:00:00 UTC, not counting leap seconds. It is a universal, timezone-independent way to represent a moment in time, widely used in server logs, databases, APIs and programming languages. The same integer means exactly the same instant everywhere — only the display changes depending on which timezone you use.

Seconds vs milliseconds (10 vs 13 digits)

Most Unix systems store time in seconds (a 10-digit number like 1700000000), but JavaScript and many modern APIs use milliseconds (a 13-digit number like 1700000000000). This tool detects which unit you have based on the magnitude of the number: under 1e12 is treated as seconds, 1e12–1e15 as milliseconds, 1e15–1e17 as microseconds, and larger as nanoseconds. If the auto-detection is wrong for your value, you can fix the unit manually.

Timezones and UTC

A Unix timestamp has no timezone — it is an absolute point in time. When you convert it to a wall-clock time, the result depends on which timezone you use. UTC is the universal reference; other timezones add or subtract an offset (e.g. UTC+09:00 for Japan Standard Time). Daylight saving time (DST) changes the offset seasonally for many timezones. This tool shows UTC, your browser's local timezone and any IANA timezone you select side by side, so you can compare them at a glance.

Features

Bidirectional conversion (epoch ↔ date)

Enter an epoch number to get the date, or enter a date to get the epoch. Both directions work instantly with no submit button. Supports ISO 8601 strings and date-only input.

Auto-detect seconds vs milliseconds (and manual override)

The unit (s / ms / µs / ns) is detected from the number of digits and shown to you. If the guess is wrong, switch the unit manually. This makes it easy to handle timestamps from different systems without guessing.

UTC, local and any IANA timezone side by side

The same moment is shown in UTC, your browser's local timezone, and a third timezone you choose from a searchable list of all IANA timezones (e.g. America/New_York, Asia/Tokyo). The UTC offset for each timezone is shown next to the time.

ISO 8601 / RFC 2822 / relative time

For each timezone, you get the ISO 8601 string with the correct offset (e.g. 2023-11-15T07:13:20+09:00), the RFC 2822 string (used in emails), a locale-friendly readable date, and a relative time (e.g. '3 hours ago', 'in 2 days'). All values can be copied with one click.

Live current epoch and 'Use now'

The current Unix epoch (seconds and milliseconds) updates every second at the top of the page. Click 'Use now' to load it into the converter instantly.

Runs entirely in your browser

All conversion happens locally. Your timestamps and dates are never sent to any server. Safe to use with sensitive log data.

Use cases

Reading Unix timestamps in server logs or database records

Paste 1700000000 from a log file or database and immediately see what date and time it represents in UTC and your local timezone. No mental arithmetic needed.

Figuring out whether a value is seconds or milliseconds (10 vs 13 digits)

If you have an unknown numeric timestamp and aren't sure of the unit, just paste it. The tool detects the unit from the digit count and shows you both the interpretation and the resulting date. Switch the unit manually if needed.

Getting the epoch for a specific date and time

Enter a date such as 2025-01-01T00:00:00Z and get the Unix second and millisecond values instantly. Useful for constructing test data, API parameters, or query conditions.

Comparing the same moment across timezones

Convert a UTC timestamp and see instantly what that moment is in Tokyo, New York, and any other city — all on one screen. Useful for scheduling, debugging distributed systems, or coordinating across teams.

Notes and limitations

• A Unix timestamp has no timezone. The same number always represents the same instant; only the wall-clock display changes.
• Auto-detection of seconds vs milliseconds is heuristic (based on digit count). If the guess is wrong, override the unit manually.
• Leap seconds are not handled — Unix time ignores leap seconds by definition, and the standard Date API follows the same convention.
• Microseconds and nanoseconds are approximated to milliseconds (lower-precision digits are lost). Values larger than Number.MAX_SAFE_INTEGER (~9×10¹⁵) may lose precision.
• Ambiguous date formats like MM/DD/YYYY are flagged — use ISO 8601 (YYYY-MM-DD) for unambiguous input.
• All input stays in your browser and is never transmitted.

Frequently asked questions

Can I convert a value that I'm not sure is seconds or milliseconds?

Yes. The tool detects the unit from the number of digits: roughly 10 digits = seconds, 13 digits = milliseconds. The detected unit is displayed. If it's wrong, switch the unit selector to the correct one.

Does it work in both directions — epoch to date and date to epoch?

Yes. Enter a number in the epoch field to get the date, or a date string in the date field to get the epoch. Both work instantly.

Can I see the result in UTC and my local timezone at the same time?

Yes. UTC and your browser's local timezone are always shown together. You can also pick any IANA timezone (e.g. Asia/Tokyo, America/New_York) from the dropdown for a third view.

Does it support ISO 8601 and RFC 2822?

Yes. For every converted timestamp, you get ISO 8601 (both UTC 'Z' form and with the timezone offset) and RFC 2822, along with a locale-friendly readable date and a relative time string.

How do I get the current Unix timestamp?

The live current epoch (seconds and milliseconds) is shown at the top of the page and updates every second. Click 'Use now' to load it into the converter.

Can it handle dates before 1970 (negative timestamps)?

Yes. Negative epoch values are valid and represent dates before 1970-01-01T00:00:00Z. For example, -1 seconds equals 1969-12-31T23:59:59Z.

Is my data sent to a server?

No. All conversion happens entirely in your browser using standard JavaScript APIs (Date, Intl). Nothing is uploaded.

How are leap seconds handled?

They aren't — and neither does Unix time by design. Unix timestamps count seconds without leap seconds, and the standard JavaScript Date API follows the same convention. The difference is tiny (a few dozen seconds over decades) and invisible for most use cases.