Unix timestamp converter

Client

Parse Unix seconds or milliseconds, or paste an ISO-8601 string—see UTC ISO, local time, and both epoch forms. Use Now for the current instant. Everything stays in your browser.

Unix timestamp & time

?

Seconds vs milliseconds: values with absolute value ≥ 1e11 are treated as milliseconds; smaller magnitudes are treated as seconds.

ISO strings are parsed with your browser's Date implementation. No data is sent to our servers.

UTC (ISO 8601)

2023-11-14T22:13:20.000Z

Local time

Nov 14, 2023, 10:13:20 PM (UTC+00:00)

Unix seconds

1700000000

Unix milliseconds

1700000000000

Enter seconds, milliseconds, or an ISO-8601 string—conversion runs locally.

Common use cases

  • Convert API logs from Unix epoch to readable UTC and local dates.
  • Check whether a timestamp is in seconds or milliseconds before storing it.
  • Verify expiration fields when debugging sessions, tokens, or cache keys.

Common mistakes to avoid

  • Mixing seconds and milliseconds

    A 10-digit epoch usually means seconds; a 13-digit epoch usually means milliseconds.

  • Comparing local and UTC without context

    Use UTC for storage and machine comparison; use local time only for display.

  • Assuming ISO text always includes timezone

    If timezone is missing, parsing may differ by environment. Prefer full ISO-8601 with Z or an offset.

FAQ

How can I tell if my epoch value is seconds or milliseconds?

Check the length first: 10 digits is usually seconds and 13 digits is usually milliseconds. If your converted date lands far in the future or past, you likely used the wrong unit.

Should I store timestamps in UTC or local time?

Store canonical values in UTC (epoch or ISO with timezone). Convert to local time only in the UI so data stays consistent across regions.

Does this converter send my timestamps to a server?

No. This page runs in your browser tab, so your input stays local to your device.

More tools

Related utilities you can open in another tab—mostly client-side.