Unix timestamp and ISO converter

Translate an incident timestamp into UTC and a selected timezone, or convert an ISO date back to Unix time. Free to use, without an account.

One instant, explicit units

Inputs stay in memory on this page. Nothing is uploaded, saved in browser storage or added to the URL. Download creates a local text file.

Input format

Result timezone

Unix timestamp (seconds)

Choose units explicitly; they are never guessed. Seconds allow up to 3 decimal places; milliseconds must be whole numbers. ISO input needs a date, time and Z or ±HH:mm offset, for example 2024-11-03T01:30:00-04:00. Changing input format clears the field.

The result timezone changes only the display, never the instant or the input offset. Daylight-saving rules come from your browser’s timezone database.

Worked example: 0 Unix seconds in UTC.

Converted instant

Input format: Unix seconds

ISO UTC: 1970-01-01T00:00:00.000Z
Unix seconds: 0
Unix milliseconds: 0
Selected timezone: UTC
Selected time (day/month/year): 01/01/1970 AD, 00:00:00.000 GMT

Seconds, milliseconds and offsets

Unix time counts elapsed time from 1970-01-01T00:00:00Z. Multiply seconds by 1,000 to get milliseconds; divide milliseconds by 1,000 to get seconds. Negative values describe instants before the epoch. This tool preserves millisecond precision and does not count leap seconds.

The number 1,000 means 1970-01-01T00:16:40.000Z in seconds mode, but 1970-01-01T00:00:01.000Z in milliseconds mode. A digit count is not proof of units. Check the system that produced your timestamp.

An offset fixes an instant: 2024-11-03T01:30:00-04:00 is 05:30 UTC, while the same clock time with -05:00 is 06:30 UTC. A bare 2024-11-03T01:30:00 is ambiguous during New York’s daylight-saving fallback, so this converter rejects it. Choosing a result timezone does not supply a missing input offset.

ISO input supports four-digit years 0000–9999, uppercase T/Z and 0–3 fractional digits. Invalid dates, leap seconds, 24:00 and the unknown offset -00:00 are rejected. Epoch input supports ±8,640,000,000,000,000 milliseconds, inclusive. UTC output outside four-digit years uses a signed six-digit ISO year; it cannot be pasted into the four-digit ISO input mode. Dates use the proleptic Gregorian calendar; regional historical rules depend on the browser’s data.

Worked examples

Epoch zero: 0 seconds → 1970-01-01T00:00:00.000Z.
Before the epoch: -1 millisecond → 1969-12-31T23:59:59.999Z, or -0.001 seconds.
Explicit offset: 2024-01-01T05:30:00+05:30 → 2024-01-01T00:00:00.000Z → 1704067200 seconds.

A converted timestamp does not verify when an incident happened, a log’s clock accuracy or monitoring coverage. This tool does not read your clipboard, fetch URLs or look up infrastructure.

For direct infrastructure reads, add a free local connection in ObserveifyNow. No account is required for connections or reads. Browser reads support published Uptime Kuma status pages; protected Proxmox VE, Proxmox Backup Server and Beszel reads require the native app, whose distribution is still in development.