Timestamp Converter
Convert between Unix timestamps and dates, both ways. Supports timezones and ms/s units.
What is the Unix Timestamp Converter?
A Unix timestamp is a number counting the seconds or milliseconds elapsed since January 1, 1970, 00:00:00 UTC (the epoch). This converter transforms a timestamp into a human-readable date, or a date into a timestamp, in both directions. It's a common need in day-to-day development: reading logs, inspecting API responses, and interpreting time fields in a database.
Its standout feature is full IANA timezone support. Pick a zone like Asia/Seoul or America/New_York and the result is shown as that region's wall-clock time, with daylight saving time (DST) handled correctly. It works with both seconds (s) and milliseconds (ms), and a 'Now' button fills in the current time in one click.
Each result includes the time in the selected timezone, a UTC ISO 8601 string, the weekday, and a relative expression like '3 minutes ago'. All computation runs on your device using only the browser's built-in Intl API, and no value is ever sent to a server.
How to use
- Choose 'Timestamp → Date' or 'Date → Timestamp' mode, then set the unit (seconds/milliseconds) and timezone.
- In Timestamp → Date, enter a numeric timestamp to see the date in the selected timezone, the UTC ISO string, the weekday, and a relative time. In Date → Timestamp, enter a value in 'YYYY-MM-DD' or 'YYYY-MM-DD HH:mm:ss' format.
- Press 'Now' to auto-fill the current time. Use the copy button next to a result to grab the value immediately.
Frequently asked questions
- How do I tell seconds from milliseconds?
- As a rule of thumb, a 10-digit number is in seconds (e.g. 1700000000) and a 13-digit number is in milliseconds (e.g. 1700000000000). Unix time is often in seconds, but JavaScript's Date.now() returns milliseconds. Select the matching unit at the top for your input.
- What changes when I switch the timezone?
- The timestamp itself is an absolute instant and doesn't change; what changes is which region's wall clock displays it. The same moment might read as 6 PM in Asia/Seoul and 5 AM in America/New_York. This tool accounts for daylight saving time to convert accurately.
- What date format should I use?
- It accepts 'YYYY-MM-DD' (e.g. 2024-01-01) or 'YYYY-MM-DD HH:mm:ss' (e.g. 2024-01-01 09:30:00). If you omit the time it is treated as 00:00:00. The date you enter is interpreted as wall-clock time in the selected timezone and converted back to the exact UTC epoch.
- What is the 'UTC (ISO 8601)' in the result?
- ISO 8601 is an international standard format for timestamps, like 2024-01-01T00:30:00.000Z, where the trailing Z means UTC. It expresses an absolute instant unambiguously regardless of timezone, which makes it ideal for storing in APIs or databases.