Runs in your browser · Last updated 4 September 2026
Unix Timestamp Converter
Convert Unix epoch seconds or milliseconds to UTC and local time, and ISO 8601 back to epoch. Client-side only.
- Detected
- seconds
- UTC
- Sun, 13 Sep 2026 14:00:18 GMT
- ISO 8601
- 2026-09-13T14:00:18.000Z
- Epoch seconds
- 1789308018
- Epoch milliseconds
- 1789308018000
- UTC date / time
- 2026-09-13 14:00:18
Current clock when this page last refreshed the “now” buttons: 2026-09-13T14:00:18.285Z
How to use this tool
- Paste seconds, milliseconds, or an ISO 8601 string.
- Or click “Use now” to capture the current epoch.
- Copy UTC, ISO, or the integer epoch from the result cards.
Formula
UTC datetime = 1970-01-01 + timestamp seconds. If you start from a Date, epoch seconds = floor(milliseconds / 1000). The sample JWT iat 1516239022 is 2018-01-18T01:30:22.000Z. Leap seconds are ignored, which is how Unix time is defined.
Frequently asked questions
- What is a Unix timestamp?
- The number of seconds (or milliseconds) since 1970-01-01T00:00:00Z. JWT iat and exp claims use seconds.
- How do you tell seconds from milliseconds?
- If the absolute value is 1e11 or more, we treat it as milliseconds. 1710000000 is seconds; 1710000000000 is milliseconds.
- Does this use my local timezone?
- The formatted strings are UTC and ISO 8601 (which is UTC with a Z). Your OS clock is only used for the “now” buttons.
- Can I paste an ISO date?
- Yes. Any string Date.parse understands, including 2018-01-18T01:30:22.000Z.
- Why convert JWT timestamps here?
- The JWT decoder shows Unix numbers. This page turns those numbers into dates you can read.