Timestamp Converter

Timestamp Converter: convert Unix time to a date

The timestamp converter turns Unix timestamps into readable dates and back. A Unix timestamp counts the seconds since 1 January 1970. The tool detects automatically whether your value is in seconds or milliseconds.

What is a Unix timestamp?

The Unix timestamp counts the seconds (or milliseconds) since 1 January 1970, 00:00:00 UTC. This single large number is independent of timezones and of language-specific date formats, which is why many databases, logs and APIs use it as their storage format. The advantage: an integer can be sorted and compared exactly. The disadvantage: numbers like 1700000000 mean nothing to a human until they are converted.

Worked example: The value 1700000000 (seconds) equals 14 November 2023, 22:13:20 UTC, that is 2023-11-14T22:13:20Z in ISO 8601. In your local timezone (Central Europe, UTC+1 in winter) that is 2023-11-14 23:13:20. Written in milliseconds the same instant is 1700000000000. The tool detects both and converts them correctly.

Two directions

• Timestamp to date: enter a number and get the date in your local timezone, in UTC, in ISO format and as relative time.
• Date to timestamp: enter a date and get the Unix value in seconds and milliseconds.

Seconds or milliseconds: detected automatically

The tool tells the units apart by magnitude: values above 10^11 (100 billion) are treated as milliseconds, smaller ones as seconds. So you do not have to remember which unit your source uses, whether logs work in seconds or some APIs return milliseconds.

ISO 8601, local time and UTC

The ISO 8601 format (2023-11-14T22:13:20Z) is the international standard and common in JavaScript, JSON and many APIs. The trailing Z stands for UTC (Zulu time). The same second count produces a different local date depending on the timezone, which is why the tool shows both separately: your local time and UTC. That way you always know which timezone is meant and avoid the classic mistake of timestamps being interpreted differently without a timezone.

Limits

The display depends on your device timezone setting. The tool does not convert between arbitrary timezones, it only shows your current local time next to UTC. The traditional Unix counter starts in 1970; earlier dates can be represented with negative values but are not specially handled here. For plain time values, the 32-bit boundary in January 2038 is a known limit, so prefer 64-bit storage.

Clicking "Use now" inserts the current timestamp or date automatically. Perfect for developers working with databases, logs or APIs.

Why does Unix time start in 1970?

The origin of the counter lies in the early days of UNIX and the wish for a compact, machine-readable time representation in operating systems. 1 January 1970 served as a practical, arbitrary reference point (the so-called epoch). Since then every second after it increases the counter by one. This format is so simple that it works identically all over the world, a major advantage over country-specific date formats.

Common time formats at a glance

Depending on the system you meet different representations of the same second. The converter converts between them:

• Unix seconds (epoch): integer, e.g. 1700000000
• Unix milliseconds: 13 digits, e.g. 1700000000000
• ISO 8601 (UTC): 2023-11-14T22:13:20Z
• Local date: depends on your timezone
• Relative: "2 hours ago", "in 3 days"

A note for developers: whether your source stores seconds or milliseconds is a convention of the application. Some APIs return seconds, others 13-digit milliseconds. The converter detects the unit by size automatically and also shows you the matching counterpart. That saves you tedious mental conversion when debugging distributed logs and avoids the classic unit trap that otherwise quickly leads to wrong date displays.

Frequently asked questions