Timestamp Converter
Convert Unix timestamps to human-readable dates and back
How to use / Why use this tool / FAQ
How to use
Enter a Unix timestamp (seconds or milliseconds) in the left field to convert it to a human-readable date and time. Or enter a date and time in the right field to convert it to a Unix timestamp. The tool automatically detects whether your input is in seconds (10 digits) or milliseconds (13 digits). Toggle the timezone selector to see the time in UTC or your local timezone. Click 'Now' to insert the current timestamp. All timestamps are clickable to copy to clipboard instantly.
Why use this tool
Unix timestamps are the universal language of time in software systems — used in database records, API responses, log files, JWT tokens, and cache expiration headers. Converting between Unix timestamps and human-readable dates is a daily task for backend developers and data engineers. This tool handles both seconds and milliseconds, supports timezone conversion, and runs entirely in your browser so you can use it offline during debugging sessions. Ideal for decoding API response timestamps, checking token expiration dates, or generating timestamps for test data.
FAQ
- What is a Unix timestamp?
- A Unix timestamp is the number of seconds (or milliseconds) elapsed since January 1, 1970, 00:00:00 UTC (the Unix epoch). It is a timezone-independent way to represent any point in time and is used universally in computer systems.
- Seconds vs milliseconds — which should I use?
- Most Unix systems use seconds. JavaScript and many APIs use milliseconds. Check your source — a 13-digit number is usually milliseconds.
- Does the timezone conversion run on the server?
- No. All conversion uses the browser's built-in Intl.DateTimeFormat API. Fully offline capable.
- How do I know if a timestamp is in seconds or milliseconds?
- Seconds timestamps have 10 digits (e.g., 1700000000). Milliseconds timestamps have 13 digits (e.g., 1700000000000). If the timestamp is too large to be a year near 2000–2100 when treated as seconds, it is likely in milliseconds.
- What is the Year 2038 problem?
- 32-bit signed integers can only store Unix timestamps up to January 19, 2038 (timestamp 2,147,483,647). Systems using 32-bit time storage will overflow after that date. Modern systems use 64-bit integers which can safely represent dates billions of years into the future.