datetime
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and ISO 8601, or convert dates back to epoch seconds.
What is Unix Timestamp Converter?
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970 — a moment known as the Unix epoch. Timestamps are the universal language of time in software: databases store them as integers, APIs return them in JSON, log files record them for every event, and JWT tokens use them for 'iat' (issued-at) and 'exp' (expiry) claims. Unlike formatted date strings, Unix timestamps are unambiguous — they have no timezone, no locale, and no format variation. JavaScript and many APIs also use millisecond timestamps (Unix seconds × 1000). This tool converts in both directions: paste a timestamp to get a human-readable date in UTC and ISO 8601, or paste a date string to get the corresponding epoch seconds and milliseconds.
How to use Unix Timestamp Converter
- Paste the timestamp or date string: Enter a Unix timestamp in seconds (e.g. 1716998400) or milliseconds (e.g. 1716998400000), or a date string in ISO 8601 format (e.g. 2024-05-29T16:00:00Z). The tool auto-detects the format.
- Read the converted output: The result shows the Unix timestamp in both seconds and milliseconds, the ISO 8601 UTC string, a human-readable UTC date, and a relative time (e.g. '3 days ago' or 'in 2 hours') calculated from the current moment.
- Copy the value you need: Click Copy next to the field you need — unix_seconds for database storage, iso8601 for API payloads, utc for display strings, or unix_ms for JavaScript Date objects.
Frequently asked questions
- How do I tell if a timestamp is in seconds or milliseconds?
- Seconds timestamps for dates after 2001 are 10 digits (≥ 1,000,000,000). Milliseconds timestamps are 13 digits (≥ 1,000,000,000,000). This tool auto-detects: any number larger than 10,000,000,000 is treated as milliseconds.
- What timezone does the output use?
- All output is in UTC. Unix timestamps have no timezone — they always count seconds from the UTC epoch. The ISO 8601 string ends with 'Z' (Zulu / UTC). To display in a local timezone, use your application's date-formatting library with a timezone identifier (e.g. 'America/New_York').
- What date formats can I convert to a Unix timestamp?
- Any string parseable by the JavaScript Date constructor: ISO 8601 (2024-05-29T16:00:00Z), RFC 2822 (Wed, 29 May 2024 16:00:00 +0000), or common formats like '2024-05-29'. Ambiguous formats like '05/29/2024' may be parsed incorrectly — prefer ISO 8601 with an explicit timezone offset.
- What is the maximum Unix timestamp?
- The 32-bit signed integer Unix timestamp overflows on 2038-01-19T03:14:07Z — the Year 2038 problem. Systems using 32-bit timestamps will wrap around to a negative number and misinterpret dates after that point. Modern systems use 64-bit integers, which will not overflow for billions of years. JavaScript's Date uses 64-bit millisecond timestamps, so web applications are not affected.
- Why do JWT tokens use Unix timestamps?
- JWT claims like 'iat' (issued at), 'exp' (expires), and 'nbf' (not before) store Unix timestamps in seconds. Using epoch seconds makes the values language-agnostic and timezone-free — a Python server, a JavaScript client, and a Go microservice all interpret 1716998400 identically as the same moment in UTC. This tool is useful for debugging JWT expiry issues: decode the token, find the 'exp' field, and paste it here to read the human-readable expiry time.
- How do I convert a timestamp to a specific timezone?
- This tool outputs UTC. To convert to a local timezone, use your language's date library: in JavaScript, new Date(timestamp * 1000).toLocaleString('en-US', { timeZone: 'America/New_York' }); in Python, datetime.fromtimestamp(timestamp, tz=ZoneInfo('Europe/Warsaw')); in Go, time.Unix(timestamp, 0).In(location).Format(time.RFC3339). Storing and transmitting timestamps in UTC is always recommended — convert to local time only at the display layer.