Convert Unix seconds or milliseconds to readable dates and convert dates back to Unix time.
-Unix seconds
-Local time
-UTC
For beginners: how to read the result
Start with the first cardIt gives the direct answer for the current mode before the longer output text.
Use the output boxCopy the exact converted value, table, header or parsed data from the output area.
Keep sensitive data localThe calculator runs in your browser, but you should still avoid secrets that your policy forbids in tools.
Paste your value, choose the mode if the calculator has one, and use the first result card as the direct answer. The longer output area is designed for copying into code, documentation, API tests or a spreadsheet.
What the result means
Short numeric input is treated as seconds; 13-digit numeric input is treated as milliseconds.
What is not included
Date parsing follows the browser. For unambiguous results, paste an ISO date such as 2026-05-24T12:30:00Z.
Privacy note
The interactive calculation runs in your browser. The page still should not be used with passwords, tokens or personal data that your own rules do not allow in browser tools.