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Timestamp Converter

Convert Unix timestamps to readable dates or convert dates to Unix time instantly in your browser. Auto-detect seconds, milliseconds, microseconds and nanoseconds (BigInt-safe), view UTC, local and IANA timezone displays with DST handling, and parse ISO 8601 strings. Private, no uploads.

Unix Timestamp

Seconds, milliseconds, microseconds or nanoseconds — auto-detected when set to Auto.

Tip: press Ctrl + Enter

A Unix timestamp represents an instant — changing the display timezone never changes the underlying instant, only its wall-clock representation.

Timestamp conversion happens locally in your browser. Timezone display uses your browser's built-in timezone data, so daylight-saving transitions are handled automatically — nothing is uploaded and no server is involved.

How it works

  1. 1Choose a mode. Use Timestamp → Date to convert a Unix timestamp into a readable date, or Date → Timestamp to convert a calendar date and time into Unix seconds, milliseconds, microseconds and nanoseconds.
  2. 2Enter your input. Paste a timestamp (seconds, milliseconds, microseconds or nanoseconds — auto-detected by magnitude) or pick a date, time and interpretation (browser local, UTC or a specific IANA timezone). An ISO 8601 string such as 2026-08-10T12:15:00+05:30 is also accepted.
  3. 3Convert. Click Convert (or press Ctrl+Enter). The result shows the ISO 8601 instant, UTC and local readable times, a selectable timezone display, day of week, relative time and all four timestamp units.
  4. 4Copy or download. Copy the ISO string, any timestamp unit, or the full conversion summary, and download a timestamp-conversion.txt file — all without leaving your browser.

Best practices

  • A Unix timestamp represents an instant — changing the display timezone never changes the instant, only its wall-clock label.
  • Ten-digit values are seconds and thirteen-digit values are milliseconds; let Auto Detect choose, or select the unit explicitly when you know it.
  • Microsecond and nanosecond timestamps are processed with BigInt to avoid precision loss; note that JavaScript dates only have millisecond precision, so sub-millisecond digits are truncated in the date output.
  • Use UTC interpretation for unambiguous machine-level conversion; use browser local or a specific IANA timezone when you need the wall-clock meaning in that zone.
  • ISO 8601 strings with Z or a numeric offset (such as +05:30) are interpreted exactly; strings without an offset follow your chosen interpretation.
  • Never treat a timestamp as an identifier for security — timestamps are predictable and reversible.
  • Everything runs locally in your browser using its built-in timezone data — nothing is uploaded.

Frequently Asked Questions

What is a Unix timestamp?
A Unix timestamp counts the number of seconds since the Unix epoch — 1970-01-01T00:00:00 UTC. A timestamp of 0 is exactly that instant; 1 is one second after it, and -1 is one second before it. This tool converts timestamps to readable dates and back, all in your browser.
What is the Unix epoch?
The Unix epoch is the reference instant 1970-01-01T00:00:00 UTC. Timestamps measure the elapsed time from this instant, so values before 1970 are negative numbers.
Are Unix timestamps in seconds or milliseconds?
Both are common. Ten-digit values (such as 1723280400) are seconds; thirteen-digit values (1723280400000) are milliseconds. This tool auto-detects seconds, milliseconds, microseconds and nanoseconds by magnitude, and also lets you select the unit explicitly.
Can this tool auto-detect the timestamp unit?
Yes. Auto Detect inspects the magnitude of the number: roughly 10 digits are seconds, 13 are milliseconds, 16 are microseconds and 19 are nanoseconds. The detected unit is always shown clearly after conversion.
Can it convert microsecond and nanosecond timestamps?
Yes. Microsecond and nanosecond values are handled with BigInt so they never lose precision to JavaScript's Number limits. JavaScript dates only have millisecond precision, so sub-millisecond digits are truncated in the date output — the tool clearly notes this when it happens.
Why do different timezones show different clock times for the same timestamp?
A timestamp represents an instant. Displaying that instant in different timezones produces different wall-clock labels (14:30 in Asia/Kolkata vs 05:00 in New York for the same instant), but the underlying instant never changes. This tool uses your browser's built-in timezone data, so daylight-saving transitions are handled automatically.
Can I convert dates before 1970?
Yes. Negative timestamps (for example -1 second) convert correctly to dates before the epoch, such as 1969-12-31T23:59:59.000Z. Both directions work before and after 1970.
Does it handle daylight saving time?
Yes. Timezone display uses the browser's built-in Intl timezone database, so DST transitions are applied automatically — never hardcoded. When converting a wall-clock time in a specific IANA timezone, spring-forward gaps and fall-back ambiguities are detected and reported instead of silently guessing.
Is my data uploaded?
No. All timestamp conversion happens locally in your browser. Nothing is sent to any server, no account is required, and the timezone data comes from your browser's built-in database.

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Supported timestamps

Convert integer and decimal timestamps in seconds, milliseconds, microseconds and nanoseconds (BigInt-safe, auto-detected by magnitude), including negative values before the epoch. Date → Timestamp accepts calendar dates and times interpreted as browser local, UTC or any IANA timezone (DST-aware via the browser's timezone database), plus strict ISO 8601-like strings such as 2026-08-10, 2026-08-10T12:15:00Z and 2026-08-10T12:15:00+05:30. The JavaScript Date range is enforced with a clear error. Everything runs locally — no uploads.

Privacy & data removal

Your timestamps, dates and timezone preferences are converted entirely in your browser and are never uploaded to any server. No account is required to use the Timestamp Converter, we never store or share your inputs, and timezone data comes from your browser's built-in database.