Does it handle dates before 1970?

Yes. Negative timestamps represent dates before the Unix epoch, and dates back to year 1 are supported for formatting.

What timezone is used?

Your local zone by default; the display-zone dropdown switches every output to any pinned IANA zone, and the Time zones tab shows the same instant everywhere at once with DST marked.

Is sub-millisecond precision kept?

Yes. Micro- and nanosecond inputs are kept as exact integers for the epoch rows and batch output; only the calendar formatting is limited to milliseconds.

Unix Timestamp Converter

Paste an epoch value in seconds, milliseconds, microseconds or nanoseconds — auto-detected with a confidence badge — or any date string, and get every representation: ISO 8601 in UTC and any zone, RFC 2822/3339, locale text, ISO week, quarter, day of year, Excel serial, .NET ticks and FILETIME. Compare the instant across pinned IANA time zones with offsets and DST flags, add or subtract time in the input's own format, format with strftime or date-fns tokens, convert whole columns in batch with CSV output, and copy ready-made JavaScript, Python, Go, SQL, PHP and Java snippets. Live relative time and a shareable link included.

Runs locally in your browser

Timestamp or date

Number unit

Pick

Enter a Unix timestamp or a date above.

Nothing to format yet.

Now (s)

—

Now (ms)

—

Now (ISO)

—

Local zone

UTC

Offset now

—

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How to use Unix Timestamp Converter

1Paste a timestamp or date, or use the picker and Now buttons.
2Read every format in the Formats tab, or compare zones side by side in Time zones (pin the ones you use).
3Use ± to shift the input, Custom format for strftime or date-fns patterns, and Batch for lists.
4Grab a code snippet for your language.

About Unix Timestamp Converter

Unix Timestamp Converter is part of FizzKit — a collection of focused developer and ad-tech tools. Because everything runs locally, it works offline once loaded and never exposes your data to a remote server.

Frequently asked questions

Auto-detect uses the digit count: 10 digits are seconds, 13 milliseconds, 16 microseconds and 19 nanoseconds. Lengths in between get a lower confidence badge, and you can force a unit from the dropdown.

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