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Unix Timestamp Converter

Translate epoch seconds or milliseconds into civil dates, or the reverse, when reading logs and JWT exp fields.

Confirm unit length—ten digits usually means seconds; thirteen often means milliseconds.

Current Unix time

Seconds: 0
Milliseconds: 0
Unit:

How to use

  1. Timestamp → Date: Enter a Unix timestamp (e.g. 1705312800 for seconds or 1705312800000 for milliseconds). The human-readable date and time appear below in UTC and your local format.
  2. Date → Timestamp: Switch to "Date → Timestamp", enter a date (e.g. 2024-01-15T12:00:00Z or "Jan 15, 2024 12:00"). The tool shows the epoch time in seconds or milliseconds.
  3. Use Share URL to copy a link with ?ts= so others can open the same timestamp.
  4. Use Copy on the current time or any result to copy the value to the clipboard.

1Epoch time keeps systems simple

Unix time counts seconds (or milliseconds) since 1970-01-01 UTC, which lets databases sort and compare instants without time zone columns for every intermediate step.

Humans prefer local civil dates; converters bridge the gap when you read server logs or API fields named created_at.

  • Confirm whether a value is in seconds or milliseconds—a ten-digit number is often seconds; thirteen digits suggests milliseconds.
  • Leap seconds and historical calendar quirks mostly disappear at the epoch layer, but presentation still needs a time zone for local clocks.

2Debugging real incidents

When a token expires “too early,” compare exp in both seconds and human time to detect mixed units between services.

Batch jobs that bucket by day must agree on whether “midnight” means UTC boundary or business-local midnight—epoch math makes that explicit.

3Storing future dates

If you store only an epoch integer, you preserve an instant; if you store a calendar date without time zone, you preserve a civil date—do not confuse the two models.

For birthdays and anniversaries, many applications store month/day without year arithmetic in UTC to avoid shifting across the date line.

4Logs and metrics

Metrics backends store timestamps in seconds or milliseconds. Mixing units between services causes charts to show events in the wrong century or cluster them at epoch zero.

5User-visible dates

Store instants in UTC; convert to local time only in the presentation layer. Birthday fields without time zone are a different model—do not store them as Unix timestamps.

6Quick checklist for epoch times

Confirm seconds vs milliseconds before comparing to JWT exp or database fields. Display results in the time zone your incident runbook uses.

  • Store instants in UTC at the persistence layer when possible.
  • Document whether APIs return string or numeric epochs.

Examples

Seconds since epoch

Typical JWT exp and Unix log format.

1700000000 → 2023-11-14 (UTC, approximate)

Milliseconds

JavaScript Date.now() returns 13-digit values.

1700000000000

Frequently asked questions

Seconds vs milliseconds: how do I tell?
Ten-digit values near current dates are usually seconds. Thirteen-digit values are usually milliseconds since epoch.
What timezone is displayed?
Conversion uses your browser’s local timezone for display unless specified otherwise. Store UTC in databases.
What is the Unix epoch?
Midnight UTC on 1 January 1970. Timestamps count from that instant.
Can I convert JWT exp claims?
Yes. Paste the numeric exp value and confirm whether it is in seconds (standard for JWT).
Do leap seconds affect Unix time?
Unix time does not count leap seconds the same way civil clocks do; most systems use smooth epoch seconds.