Unix Timestamps Explained: Everything Developers Need to Know
What Unix timestamps are, why they exist, and how to work with them.
Convert between Unix timestamps and dates
0Accepts timestamps in seconds or milliseconds. Date strings can be ISO 8601 or other parseable formats.
2 articles to help you understand and use this tool effectively
Common questions about using the Unix Timestamp Converter tool
A Unix timestamp is the number of seconds (or milliseconds) since January 1, 1970, 00:00:00 UTC (the Unix epoch). It's a universal way to represent time as a single number, independent of timezone, used extensively in programming and databases.
To convert a timestamp: 1) Enter the Unix timestamp, 2) Select seconds or milliseconds, 3) See the human-readable date instantly. In JavaScript: new Date(timestamp * 1000) for seconds, new Date(timestamp) for milliseconds.
In JavaScript: Date.now() returns milliseconds, Math.floor(Date.now() / 1000) for seconds. In Python: import time; time.time(). In command line: date +%s (Unix/Mac). Our tool shows the current timestamp updating in real-time.
Seconds timestamps are 10 digits (e.g., 1705276800), milliseconds are 13 digits (e.g., 1705276800000). JavaScript Date uses milliseconds, Unix traditionally uses seconds. Check digit count to determine format. Our tool auto-detects and handles both.
Enter a date/time in the input field and get the timestamp. In JavaScript: new Date('2024-01-15').getTime() for milliseconds, divide by 1000 for seconds. Use Date.UTC() for UTC-based conversion without timezone offset.
32-bit systems store timestamps as signed integers, maxing out at 2,147,483,647 (January 19, 2038, 03:14:07 UTC). After this, timestamps overflow and become negative. 64-bit systems extend this by billions of years. Most modern systems are 64-bit.
Unix timestamps are always UTC - they represent a single moment in time. When displaying, convert to local timezone: new Date(timestamp * 1000).toLocaleString(). Store/transmit as UTC, convert to local only for display.
ISO 8601 is the international standard format: 2024-01-15T14:30:00Z. The T separates date and time, Z indicates UTC. With offset: 2024-01-15T14:30:00+05:30. It's unambiguous, sortable, and widely supported. Use toISOString() in JavaScript.
Subtract timestamps to get difference in seconds/milliseconds. Convert to meaningful units: diff / 60 for minutes, / 3600 for hours, / 86400 for days. For complex calculations (months, years), use libraries like date-fns or Luxon.
Yes, negative timestamps represent dates before January 1, 1970. For example, -86400 is December 31, 1969. JavaScript handles negative timestamps correctly: new Date(-86400000) works. Useful for historical dates.