What this tool does
Unix time counts seconds since 1 January 1970 UTC, and it appears in almost every API, database column, and log file. This tool converts in both directions and shows the result in the formats you are likely to need: ISO 8601, local time, UTC, RFC 2822, and relative time.
How it works
A Unix timestamp is a count, not a calendar date, so it has no timezone of its own. The same number is a different moment depending on where you are standing, which is why this tool always shows both the local time and the UTC time. When storing or comparing timestamps, keep them in UTC and convert only for display.
The unit matters as much as the number. A 10-digit value is almost always seconds, a 13-digit value milliseconds, and microseconds run to 16 digits. Feeding milliseconds to code expecting seconds produces a date in the year 55000, so the unit is detected from the digit count and shown explicitly.
Note the 2038 problem: 32-bit signed seconds run out in January 2038. A 32-bit millisecond counter runs out in 1970 plus about 24 days of uptime, which is why many systems store milliseconds as 64-bit values or as an interval type.
Worked example
Decoding 1714569600 from an API response.
- 10 digits, so the unit is seconds
- Interpret as seconds since 1970-01-01T00:00:00Z
- Convert to a date and render in local time and UTC
2024-05-01T00:00:00Z in UTC, with the local rendering offset by your timezone.
Accuracy and limitations
- A bare timestamp carries no timezone. Confirm the intended zone before comparing values from different systems.
- JavaScript's Date has millisecond precision. Microsecond and nanosecond timestamps lose their lowest digits when parsed in the browser.
- The 32-bit second range ends in January 2038, which is a real risk for systems that have not moved to 64-bit time.
Frequently asked questions
- How do I tell if a timestamp is seconds or milliseconds?
- By its length. Ten digits is seconds, thirteen is milliseconds, sixteen is microseconds, nineteen is nanoseconds. The tool detects this and labels the unit, because getting it wrong shifts the date by decades.
- What is the Unix epoch?
- Midnight UTC on 1 January 1970, which is timestamp zero. The choice was arbitrary; it fell on a Thursday, and the date has no significance beyond being a convenient reference point.
- Why is my timestamp showing the wrong date?
- Almost always a unit mismatch. A millisecond value read as seconds lands thousands of years in the future, and a seconds value read as milliseconds lands in 1970. The tool shows the detected digit count and the interpreted unit to make that visible.
- Does this run in my timezone?
- Both are shown. The UTC value is the one that is unambiguous and the one you should store; the local value is for reading. Server logs and API payloads are conventionally UTC.